Old Irish

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Old Irish
Old Gaelic
RegionIreland, Isle of Man, Wales, Scotland
Era6th century–10th century; evolved into Middle Irish about the 10th century
Early form
Language codes
ISO 639-2sga
ISO 639-3sga
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Old Irish, also called Old Gaelic[1][2][3] (Goídelc; Ogham: ᚌᚑᚔᚇᚓᚂᚉ; Irish: Sean-Ghaeilge; Scottish Gaelic: Seann-Ghàidhlig; Manx: Shenn Yernish or Shenn Ghaelg), is the oldest form of the Goidelic/Gaelic language for which there are extensive written texts. It was used from c. 600 to c. 900. The main contemporary texts are dated c. 700–850; by 900 the language had already transitioned into early Middle Irish. Some Old Irish texts date from the 10th century, although these are presumably copies of texts written at an earlier time. Old Irish is thus forebear to Modern Irish, Manx, and Scottish Gaelic.[2]

Old Irish is known for having a particularly complex system of morphology and especially of allomorphy (more or less unpredictable variations in stems and suffixes in differing circumstances) as well as a complex sound system involving grammatically significant consonant mutations to the initial consonant of a word. Apparently,[* 1] neither characteristic was present in the preceding Primitive Irish period, though initial mutations likely existed in a non-grammaticalized form in the prehistoric era.[4] Much of the complex allomorphy was subsequently lost, but the sound system has been maintained with little change in the modern languages.[citation needed]

Contemporary Old Irish scholarship is still greatly influenced by the works of a small number of scholars active in the late 19th and early 20th centuries such as Rudolf Thurneysen (1857–1940) and Osborn Bergin (1873–1950).

Notable characteristics[edit]

Notable characteristics of Old Irish compared with other old Indo-European languages, are:

  • Initial mutations, including lenition, nasalisation and aspiration/gemination.
  • A complex system of verbal allomorphy.[5]
  • A system of conjugated prepositions that is unusual in Indo-European languages but common to Celtic languages. There is a great deal of allomorphy here, as well.
  • Infixed object prepositions, which are inserted between the verb stem and its prefix(es). If a verb lacks any prefixes, a dummy prefix is normally added.
  • Special verbal conjugations are used to signal the beginning of a relative clause.

Old Irish also preserves most aspects of the complicated Proto-Indo-European (PIE) system of morphology. Nouns and adjectives are declined in three genders (masculine, feminine, neuter); three numbers (singular, dual, plural); and five cases (nominative, vocative, accusative, dative and genitive). Most PIE noun stem classes are maintained (o-, yo-, ā-, -, i-, u-, r-, n-, s-, and consonant stems). Most of the complexities of PIE verbal conjugation are also maintained, and there are new complexities introduced by various sound changes (see below).


Old Irish was the only member of the Goidelic branch of the Celtic languages, which is, in turn, a subfamily of the wider Indo-European language family that also includes the Slavonic, Italic/Romance, Indo-Aryan and Germanic subfamilies, along with several others. Old Irish is the ancestor of all modern Goidelic languages: Modern Irish, Scottish Gaelic and Manx.

A still older form of Irish is known as Primitive Irish. Fragments of Primitive Irish, mainly personal names, are known from inscriptions on stone written in the Ogham alphabet. The inscriptions date from about the 4th to the 6th centuries. Primitive Irish appears to have been very close to Common Celtic, the ancestor of all Celtic languages, and it had a lot of the characteristics of other archaic Indo-European languages.


Relatively little survives in the way of strictly contemporary sources. They are represented mainly by shorter or longer glosses on the margins or between the lines of religious Latin manuscripts, most of them preserved in monasteries in Germany, Italy, Switzerland, France and Austria, having been taken there by early Irish missionaries. Whereas in Ireland, many of the older manuscripts appear to have been worn out through extended and heavy use, their counterparts on the Continent were much less prone to the same risk because once they ceased to be understood, they were rarely consulted.[6]

The earliest Old Irish passages may be the transcripts found in the Cambrai Homily, which is thought to belong to the early 8th century. The Book of Armagh contains texts from the early 9th century. Important Continental collections of glosses from the 8th and 9th century include the Würzburg Glosses (mainly) on the Pauline Epistles, the Milan Glosses on a commentary to the Psalms and the St Gall Glosses on Priscian's Grammar.

Further examples are found at Karlsruhe (Germany), Paris (France), Milan, Florence and Turin (Italy). A late 9th-century manuscript from the abbey of Reichenau, now in St. Paul in Carinthia (Austria), contains a spell and four Old Irish poems. The Liber Hymnorum and the Stowe Missal date from about 900 to 1050.

In addition to contemporary witnesses, the vast majority of Old Irish texts are attested in manuscripts of a variety of later dates. Manuscripts of the later Middle Irish period, such as the Lebor na hUidre and the Book of Leinster, contain texts, which are thought to derive from written exemplars in Old Irish now lost and retain enough of their original form to merit classification as Old Irish.

The preservation of certain linguistic forms current in the Old Irish period may provide reason to assume that an Old Irish original directly or indirectly underlies the transmitted text or texts.



The consonant inventory of Old Irish is shown in the chart below. The complexity of Old Irish phonology is from a four-way split of phonemes inherited from Primitive Irish, with both a fortis–lenis and a "broad–slender" (velarised vs. palatalised) distinction arising from historical changes. The sounds /f v θ ð x ɣ h ṽ n l r/ are the broad lenis equivalents of broad fortis /p b t d k ɡ s m N L R/; likewise for the slender (palatalised) equivalents. (However, most /f fʲ/ sounds actually derive historically from /w/.)

Labial Dental Alveolar Velar Glottal
Nasal broad m N  n ŋ
slender Nʲ  nʲ ŋʲ
Plosive broad p  b t  d k  ɡ
slender pʲ  bʲ tʲ  dʲ kʲ  ɡʲ
Fricative broad f  v θ  ð s x  ɣ h
slender fʲ  vʲ θʲ  ðʲ xʲ  ɣʲ
slender ṽʲ
Approximant broad R  r
slender Rʲ  rʲ
Lateral broad L  l
slender Lʲ  lʲ

Some details of Old Irish phonetics are not known. /sʲ/ may have been pronounced [ɕ] or [ʃ], as in Modern Irish. /hʲ/ may have been the same sound as /h/ or /xʲ/. The precise articulation of the fortis sonorants /N/, /Nʲ/, /L/, /Lʲ/, /R/, /Rʲ/ is unknown, but they were probably longer, tenser and generally more strongly articulated than their lenis counterparts /n/, /nʲ/, /l/, /lʲ/, /r/, /rʲ/, as in the Modern Irish and Scottish dialects that still possess a four-way distinction in the coronal nasals and laterals. /Nʲ/ and /Lʲ/ may have been pronounced [ɲ] and [ʎ] respectively. The difference between /R(ʲ)/ and /r(ʲ)/ may have been that the former were trills while the latter were flaps. /m(ʲ)/ and /ṽ(ʲ)/ were derived from an original fortis–lenis pair.


Old Irish had distinctive vowel length in both monophthongs and diphthongs. Short diphthongs were monomoraic, taking up the same amount of time as short vowels, while long diphthongs were bimoraic, the same as long vowels. (This is much like the situation in Old English but different from Ancient Greek whose shorter and longer diphthongs were bimoraic and trimoraic, respectively: /ai/ vs. /aːi/.) The inventory of Old Irish long vowels changed significantly over the Old Irish period, but the short vowels changed much less.

The following short vowels existed:

Monophthongs Diphthongs
Close i u ĭu
Mid e o ĕu (ŏu)1
Open a, (æ ~ œ?) ău

1The short diphthong ŏu may have existed very early in the Old Irish period/but not later on.

/æ ~ œ/ arose from the u-infection of stressed /a/ by a /u/ that preceded a palatalized consonant. This vowel faced much inconsistency in spelling, often detectable by a word containing it being variably spelled with au, ai, e, i, or u across attestations. Tulach "hill, mound" is the most commonly cited example of this vowel, with the spelling of its inflections including tulach itself, telaig, telocho, tilchaib, taulich and tailaig. This special vowel also ran rampant in many words starting with the stressed prefix air- (from Proto-Celtic *ɸare).[7][8]

Archaic Old Irish (before about 750) had the following inventory of long vowels:

Monophthongs Diphthongs
Close iu ui
Mid e₁ː, e₂ː1 o₁ː, (o₂ː?)2 eu oi, (ou)3
Open ai, au3

1Both /e₁ː/ and /e₂ː/ were normally written é but must have been pronounced differently because they have different origins and distinct outcomes in later Old Irish. /e₁ː/ stems from Proto-Celtic *ē (< PIE *ei), or from ē in words borrowed from Latin. e₂ː generally stems from compensatory lengthening of short *e because of loss of the following consonant (in certain clusters) or a directly following vowel in hiatus. It is generally thought that /e₁ː/ was higher than /e₂ː/.[9] Perhaps /e₁ː/ was [eː] while /e₂ː/ was [ɛː]. They are clearly distinguished in later Old Irish, in which /e₁ː/ becomes ía (but é before a palatal consonant). /e₂ː/ becomes é in all circumstances. Furthermore, /e₂ː/ is subject to u-affection, becoming éu or íu, while /e₁ː/ is not.

2A similar distinction may have existed between /o₁ː/ and /o₂ː/, both written ó, and stemming respectively from former diphthongs (*eu, *au, *ou) and from compensatory lengthening. However, in later Old Irish both sounds appear usually as úa, sometimes as ó, and it is unclear whether /o₂ː/ existed as a separate sound any time in the Old Irish period.

3/ou/ existed only in early archaic Old Irish (c.700 or earlier); afterwards it merged into /au/. Neither sound occurred before another consonant, and both sounds became ó in later Old Irish (often ú or u before another vowel). The late ó does not develop into úa, suggesting that áu > ó postdated ó > úa.

Later Old Irish had the following inventory of long vowels:

Monophthongs Diphthongs
Close iu, ia ui, ua
Mid eu oi?1

1Early Old Irish /ai/ and /oi/ merged in later Old Irish. It is unclear what the resulting sound was, as scribes continued to use both and to indicate the merged sound. The choice of /oi/ in the table above is somewhat arbitrary.

The distribution of short vowels in unstressed syllables is a little complicated. All short vowels may appear in absolutely final position (at the very end of a word) after both broad and slender consonants. The front vowels /e/ and /i/ are often spelled ae and ai after broad consonants, which might indicate a retracted pronunciation here, perhaps something like [ɘ] and [ɨ]. All ten possibilities are shown in the following examples:

Old Irish Pronunciation English Annotations
marba /ˈmarva/ kill 1 sg. subj.
léicea /ˈLʲeːɡʲa/ leave 1 sg. subj.
marbae /ˈmarve/ ([ˈmarvɘ]?) kill 2 sg. subj.
léice /ˈLʲeːɡʲe/ leave 2 sg. subj.
marbai /ˈmarvi/ ([ˈmarvɨ]?) kill 2 sg. indic.
léici /ˈlʲeːɡʲi/ leave 2 sg. indic.
súlo /ˈsuːlo/ eye gen.
doirseo /ˈdoRʲsʲo/ door gen.
marbu /ˈmarvu/ kill 1 sg. indic.
léiciu /ˈLʲeːɡʲu/ leave 1 sg. indic.

The distribution of short vowels in unstressed syllables, other than when absolutely final, was quite restricted. It is usually thought that there were only two allowed phonemes: /ə/ (written a, ai, e or i depending on the quality of surrounding consonants) and /u/ (written u or o). The phoneme /u/ tended to occur when the following syllable contained an *ū in Proto-Celtic (for example, dligud /ˈdʲlʲiɣuð/ "law" (dat.) < PC *dligedū), or after a broad labial (for example, lebor /ˈLʲevur/ "book"; domun /ˈdoṽun/ "world"). The phoneme /ə/ occurred in other circumstances. The occurrence of the two phonemes was generally unrelated to the nature of the corresponding Proto-Celtic vowel, which could be any monophthong: long or short.

Long vowels also occur in unstressed syllables. However, they rarely reflect Proto-Celtic long vowels, which were shortened prior to the deletion (syncope) of inner syllables. Rather, they originate in one of the following ways:

  • from the late resolution of a hiatus of two adjacent vowels (usually as a result of loss of *s between vowels);
  • from compensatory lengthening in response to loss of a consonant (cenél "kindred, gender" < *cenethl; du·air-chér "I have purchased" < *-chechr, preterite of crenaid "buys"[10]);
  • from assimilation of an unstressed vowel to a corresponding long stressed vowel;
  • from late compounding;
  • from lengthening of short vowels before unlenited /m, N, L, R/, still in progress in Old Irish (compare erríndem "highest" vs. rind "peak"[11]).


Stress is generally on the first syllable of a word. However, in verbs it occurs on the second syllable when the first syllable is a clitic (the verbal prefix as- in as·beir /asˈberʲ/ "he says"). In such cases, the unstressed prefix is indicated in grammatical works with a following centre dot (·).


As with most medieval languages, the orthography of Old Irish is not fixed, so the following statements are to be taken as generalisations only. Individual manuscripts may vary greatly from these guidelines.

The Old Irish alphabet consists of the following eighteen letters of the Latin alphabet:

a, b, c, d, e, f, g, h, i, l, m, n, o, p, r, s, t, u,

in addition to the five long vowels, shown by an acute accent (´):

á, é, í, ó, ú,

the lenited consonants denoted with a superdot (◌̇):

ḟ, ṡ,

and the eclipsis consonants also denoted with a superdot:

ṁ, ṅ.

Old Irish digraphs include the lenition consonants:

ch, fh, th, ph, sh,

the eclipsis consonants:

mb, nd, ng; ṁb, ṅd, ṅg,

the geminatives:

bb, cc, ll, mm, nn, pp, rr, tt,

and the diphthongs:

aé/áe/aí/ái, oé/óe/oí/ói,
uí, ía, áu, úa, éu, óu, iu, au, eu,
ai, ei, oi, ui; ái, éi, ói, úi.

The following table indicates the broad pronunciation of various consonant letters in various environments:

Broad consonant phonemes
Letter Word-initial Non-initial
unmutated eclipsed lenited single geminate
b /b/ ⟨mb⟩ /m/ /v/ ⟨bb⟩ /b/
c /k/ /ɡ/ ⟨ch⟩ /x/ /k/, /ɡ/ ⟨cc⟩ /k/
d /d/ ⟨nd⟩ /N/ /ð/
f /f/ /v/ ⟨ḟ/fh⟩ / / /f/
g /ɡ/ ⟨ng⟩ /ŋ/ /ɣ/
h See explanation below
l /L/ /l/ ⟨ll⟩ /L/
m /m/ // ⟨mm⟩ /m/
n /N/ /n/ ⟨nn⟩ /N/
p /p/ /b/ ⟨ph⟩ /f/ /p/, /b/ ⟨pp⟩ /p/
r /R/ /r/ ⟨rr⟩ /R/
s /s/ ⟨ṡ/sh⟩ /h/ /s/
t /t/ /d/ ⟨th⟩ /θ/ /t/, /d/ ⟨tt⟩ /t/
Angle brackets ⟨⟩ here indicate graphemic differences to the unmutated consonant.
A dash (—) here indicates that the respective consonant is not subject to eclipsis. These consonants are: r, l, n, s[12]

When the consonants b, d, g are eclipsed by the preceding word (always from a word-initial position), their spelling and pronunciation change to: ⟨mb⟩ /m/, ⟨nd⟩ /N/, ⟨ng⟩ /ŋ/[12]

Generally, geminating a consonant ensures its unmutated sound. While the letter ⟨c⟩ may be voiced /ɡ/ at the end of some words, but when it's written double ⟨cc⟩ it's always voiceless /k/ in regularised texts; however, even final /ɡ/ was often written "cc", as in bec / becc "small, little" (Modern Irish and Scottish beag, Manx beg).

In later Irish manuscripts, lenited f and s are denoted with the letter h ⟨fh⟩, ⟨sh⟩, instead of using a superdot ⟨ḟ⟩, ⟨ṡ⟩.[12]

When initial s stemmed from Primitive Irish *sw-, its lenited version is ⟨f⟩ [ɸ].

The slender (palatalised) variants of the 13 consonants are denoted with /ʲ/ marking the letter. They occur in the following environments:

  • Before a written e, é, i, í
  • After a written i, when not followed by a vowel letter (but not after the diphthongs aí, oí, uí)

Although Old Irish has both a sound /h/ and a letter h, there is no consistent relationship between the two. Vowel-initial words are sometimes written with an unpronounced h, especially if they are very short (the Old Irish preposition i "in" was sometimes written hi) or if they need to be emphasised (the name of Ireland, Ériu, was sometimes written Hériu). On the other hand, words that begin with the sound /h/ are usually written without it: a ór /a hoːr/ "her gold". If the sound and the spelling co-occur, it is by coincidence, as ní hed /Nʲiː heð/ "it is not".

Stops following vowels[edit]

The voiceless stops of Old Irish are c, p, t. They contrast with the voiced stops g, b, d. Additionally, the letter m can behave similarly to a stop following vowels. These seven consonants often mutate when not in the word-initial position.

In non-initial positions, the single-letter voiceless stops c, p, and t become the voiced stops /ɡ/, /b/, and /d/ respectively unless they are written double. Ambiguity in these letters' pronunciations arises when a single consonant follows an l, n, or r.[12] The lenited stops ch, ph, and th become /x/, /f/, and /θ/ respectively.

Non-initial voiceless stops ⟨c⟩, ⟨p⟩, ⟨t⟩
Old Irish Pronunciation English
macc /mak/ son
bec or becc /bʲeɡ/ small
op or opp /ob/ refuse
bratt /brat/ mantle
brot or brott /brod/ goad
Lenited consonants ⟨ch⟩, ⟨ph⟩, ⟨th⟩
ech /ex/ horse
oíph /oif/ beauty
áth /aːθ/ ford

The voiced stops b, d, and g become fricative /v/, /ð/, and /ɣ/, respectively—identical sounds to their word-initial lenitions.

Non-initial voiced stops ⟨g⟩, ⟨b⟩, ⟨d⟩
Old Irish Pronunciation English
dub /duv/ black
mod /moð/ work
mug /muɣ/ slave
claideb /klaðʲəv/ sword
claidib /klaðʲəvʲ/ swords

In non-initial positions, the letter m usually becomes the nasal fricative //, but in some cases it becomes a nasal stop, denoted as /m/. In cases in which it becomes a stop, m is often written double to avoid ambiguity.

Non-initial consonant ⟨m⟩
Old Irish Pronunciation English
dám /daːṽ/ company
lom or lomm /Lom/ bare

Stops following other consonants[edit]

Ambiguity arises in the pronunciation of the stop consonants (c, g, t, d, p, b) when they follow l, n, or r:

Homographs involving ⟨l⟩, ⟨n⟩, ⟨r⟩
Old Irish Pronunciation English
derc /dʲerk/ hole
derc /dʲerɡ/ red
daltae /daLte/ fosterling
celtae /kʲeLde/ who hide
anta /aNta/ of remaining
antae /aNde/ who remain

After m, the letter b is naturally a stop /b/. After d, l, r, the letter b is fricative /v/:

Consonant ⟨b⟩
Old Irish Pronunciation English
imb /imʲbʲ/ butter
odb /oðv/ knot (in a tree)
delb /dʲelv/ image
marb /marv/ dead

After n or r, the letter d is a stop /d/:

Consonant ⟨d⟩
Old Irish Pronunciation English
bind /bʲiNʲdʲ/ melodious
cerd /kʲeRd/ art, skill

After n, l, or r, the letter g is usually a stop /ɡ/, but it becomes a fricative /ɣ/ in a few words:

Consonant ⟨g⟩
Old Irish Pronunciation English
long /Loŋɡ/ ship
delg or delc /dʲelɡ/ thorn
argat or arggat /arɡəd/ silver
ingen[* 2] /inʲɣʲən/ daughter
ingen[* 2] /iNʲɡʲən/ nail, claw
bairgen /barʲɣʲən/ loaf of bread

The consonants l, n, r[edit]

The letters l, n, r are generally written double when they indicate tense sonorants and single when they indicate lax sonorants. Originally, it reflected an actual difference between single and geminate consonants, as tense sonorants in many positions (such as between vowels or word-finally) developed from geminates. As the gemination was lost, the use of written double consonants was repurposed to indicate tense sonorants. Doubly written consonants of this sort do not occur in positions where tense sonorants developed from non-geminated Proto-Celtic sonorants (such as word-initially or before a consonant).

Old Irish Pronunciation English
corr /koR/ crane
cor /kor/ putting
coll /koL/ hazel
col /kol/ sin
sonn /soN/ stake
son /son/ sound
ingen[* 2] /inʲɣʲən/ daughter
ingen[* 2] /iNʲɡʲən/ nail, claw

Geminate consonants appear to have existed since the beginning of the Old Irish period, but they were simplified by the end, as is generally reflected by the spelling. Although, ll, mm, nn, rr were eventually repurposed to indicate nonlenited variants of those sounds in certain positions.


Written vowels a, ai, e, i in poststressed syllables (except when absolutely word-final) all seem to represent phonemic /ə/. The particular vowel that appears is determined by the quality (broad vs. slender) of the surrounding consonants and has no relation to the etymological vowel quality:

Preceding consonant Following consonant Spelling Example
broad broad ⟨a⟩ dígal /ˈdʲiːɣəl/ "vengeance" (nom.)
broad slender (in open syllable) ⟨a⟩
broad slender (in closed syllable) ⟨ai⟩ dígail /ˈdʲiːɣəlʲ/ "vengeance" (acc./dat.)
slender broad ⟨e⟩ dliged /ˈdʲlʲiɣʲəð/ "law" (acc.)
slender slender ⟨i⟩ dligid /ˈdʲlʲiɣʲəðʲ/ "law" (gen.)

It seems likely that spelling variations reflected allophonic variations in the pronunciation of /ə/.


Old Irish was affected by a series of phonological changes that radically altered its appearance compared with Proto-Celtic and older Celtic languages (such as Gaulish, which still had the appearance of typical early Indo-European languages such as Latin or Ancient Greek). The changes were such that Irish was not recognized as Indo-European at all for much of the 19th century. The changes must have happened quite rapidly, perhaps in only one or two hundred years around 500–600, because almost none of the changes are visible in Primitive Irish (4th to 6th centuries), and all of them are already complete in archaic Old Irish (8th century). A capsule summary of the most important changes is (in approximate order):[13][14]

  1. Syllable-final *n (from PIE *m, *n) assimilated to the following phoneme, even across word boundaries in the case of syntactically connected words.
    • Voiceless stops became voiced: *mp *nt *nk > /b d ɡ/.
    • Voiced stops became prenasalised /ᵐb, ⁿd, ᵑɡ/. They were reduced to simple nasals during the Old Irish period.
    • Before a vowel, /n-/ was attached to the beginning of the syllable.
  2. Lenition of all single consonants between vowels. That applied across word boundaries in the case of syntactically connected words.
    • Stops became fricatives.
    • *s became /h/ (later lost unless the following syllable was stressed).
    • *w was eventually lost (much later).
    • *m became a nasalised continuant (/w̃/; perhaps [w̃] or [β̃]).
    • *l *n *r remained, but the non-lenited variants were strengthened to /L N R/ (see phonology section above).
  3. Extensive umlaut ("affection") of short vowels, which were raised or lowered to agree with the height of following Proto-Celtic vowels. Similarly, rounding of *a to /o/ or /u/ often occurred adjacent to labial consonants.
  4. Palatalization of all consonants before front vowels.
  5. Loss of part or all of final syllables.
  6. Loss of most interior vowels (syncope).

They led to the following effects:

  • Both the palatalised ("slender") and lenited variants of consonants were phonemicised, multiplying the consonant inventory by four (broad, broad lenited, slender, slender lenited). Variations between broad and slender became an important part of the grammar:
    • in masc. o-stems: macc "son" (nom. acc.) vs. maicc (gen.), cúl "back" (nom. acc.) vs. cúil (gen.), cf. Latin -us (nom.), -um (acc.) vs. (gen.);
    • in fem. ā-stems: túath "tribe, people" (nom.) vs. túaith (acc. dat.), mucc "pig" (nom.) vs. muicc (acc. dat.);
    • in r-stems: athar "father" (gen.) vs. ath(a)ir (nom. acc. dat.).
  • Lenition and nasal assimilation across word boundaries in syntactically connected words produced extensive sandhi effects (Irish initial mutations). The variations became an important part of the grammar.
  • Both umlaut (vowel affection) and especially syncope radically increased the amount of allomorphy found across declensions and conjugations. The most dramatic deviations are due to syncope: compare as·berat "they say" vs. ní-epret "they do not say" or do·sc(a)i "he surpasses" vs. ní-derscaigi "he does not surpass" (where the stressed syllable is boldfaced).

Examples of changes[edit]

The following are some examples of changes between Primitive Irish and Old Irish.

Primitive Irish Old Irish Meaning
inigena[15] ingen daughter
qrimitir[16] cruimther priest
maqqi[17] maicc son (gen.)
velitas[18] filed poet (gen.)
Lugudeccas[19] Luigdech genitive of Lug(u)id (name)
Anavlamattias[20] Anfolmithe genitive of Anblamath (name)
Coillabotas[21] Coílbad genitive of name


These various changes, especially syncope, produced quite complex allomorphy, because the addition of prefixes or various pre-verbal particles (proclitics) in Proto-Celtic changed the syllable containing the stress: According to the Celtic variant of Wackernagel's law, the stress fell on the second syllable of the verbal complex, including any prefixes and clitics. By the Old Irish period, most of this allomorphy still remained, although it was rapidly eliminated beginning in the Middle Irish period.

Among the most striking changes are in prefixed verbs with or without pre-verbal particles. With a single prefix and without a proclitic, stress falls on the verbal root, which assumes the deuterotonic ("second-stressed") form. With a prefix and also with a proclitic, stress falls on the prefix, and the verb assumes the prototonic ("first-stressed") form. Rather extreme allomorphic differences can result:

Example differences between deuterotonic and prototonic forms of various verbs. Stress falls directly after the center dot or hyphen.[22]
Earlier form Deuterotonic Meaning Prototonic Meaning
*ess-bero(n)t < PIE *-bʰeronti as·berat /as-ˈbʲerəd/ they say ní-epret /Nʲiː-ˈhebrʲəd/ they do not say
*cum-uss-ana con·osna he rests ní-cumsana he does not rest
*de-ro-uss-scochi do·rósc(a)i he surpasses ní-derscaigi he does not surpass
*de-lugi < PIE *-logʰeyeti do·lug(a)i he pardons ní-dílg(a)i he does not pardon
*de-ro-gn... do·róna he may do ní-derna he may not do

The following table shows how these forms might have been derived:

Possible derivation of some verbal forms
"they say" "they do not say" "he rests" "he does not rest" "he surpasses" "he does not surpass"
Post-PIE eks bʰeronti nē eks bʰeronti kom uks h₂eneh₂ti nē kom uks h₂eneh₂ti dē pro uks skokeyeti nē dē pro uks skokeyeti
Proto-Celtic eks ˈberonti nī ˈeks-beronti kom ˈuks-anāti nī ˈkom-uks-anāti dī ˈɸro-uks-skokīti nī ˈdī-ɸro-uks-skokīti
Early Irish ess-es ˈberont ní-s ˈess-beront kon-es ˈuss-anát ní-s ˈkom-uss-anát dí-s ˈro-uss-skokít ní-s ˈdi-ro-uss-skokít
Nasal assimilation ess-es ˈberodd ní-s ˈess-berodd
Lenition es-eh ˈberod Ní-h ˈes-berod kon-eh ˈus-anáθ Ní-h ˈkow̃-us-anáθ dí-h ˈRo-us-skoxíθ Ní-h ˈdi-ro-us-skoxíθ
Palatalization es-eh ˈbʲerod Nʲí-h ˈes-bʲerod Nʲí-h ˈkow̃-us-anáθ dʲí-h ˈRo-us-skoxʲíθ Nʲí-h ˈdʲi-ro-us-skoxʲíθ
Hiatus reduction dʲí-h ˈRós-skoxʲíθ Nʲí-h ˈdʲi-rós-skoxʲíθ
Umlaut (vowel affection) kon-eh ˈos-anáθ Nʲí-h ˈkuw̃-us-anáθ Nʲí-h ˈdʲe-rós-skoxʲíθ
Shortening of absolutely final vowel
Loss/assimilation of final consonant(s) es-e bʲ-ˈbʲerod Nʲí h-ˈes-bʲerod kon-e h-ˈos-aná Nʲí k-ˈkuw̃-us-aná dʲí R-ˈRós-skoxʲí Nʲí d-ˈdʲe-rós-skoxʲí
Mora reduction in unstressed final vowel es bʲ-ˈbʲerod kon h-ˈos-ana Nʲí k-ˈkuw̃-us-ana dʲí R-ˈRós-skoxʲi Nʲí d-ˈdʲe-rós-skoxʲi
Consonant assimilation es ˈbʲerod Nʲí h-ˈebʲ-bʲerod
Syncope es ˈbʲerod Nʲí h-ˈebʲbʲrod kon h-ˈosna Nʲí k-ˈkuw̃sana dʲí R-ˈRósskxʲi Nʲíd-ˈdʲersskoxʲi
Further consonant assimilation Nʲí h-ˈebʲbʲrʲod kon ˈosna dʲí R-ˈRósski Nʲíd-ˈdʲerskoxʲi
Unstressed vowel reduction es ˈbʲerəd Nʲí h-ˈebʲbʲrʲəd Nʲí k-ˈkuw̃səna di R-ˈRósski Nʲí d-ˈdʲerskəxʲi
Prepositional modification as ˈbʲerəd do R-ˈRósski
Geminate reduction (non-vocalic-adjacent); sandhi geminate reduction as·ˈbʲerəd Nʲíh-ˈebrʲəd kon·ˈosna Nʲí-ˈkuw̃səna do·ˈRóski Nʲí-ˈdʲerskəxʲi
Fricative voicing between unstressed syllables Nʲíd-ˈdʲerskəɣʲi
Old Irish pronunciation as·ˈbʲerəd Nʲí-h-ˈebrʲəd kon·ˈosna Nʲí-ˈkuw̃səna do·ˈRóski Nʲí-ˈdʲerskəɣʲi
Old Irish spelling as·berat ní-epret con·osna ní-(c)cumsana do·rósc(a)i ní-(d)derscaigi

The most extreme allomorphy of all came from the third person singular of the s-subjunctive because an athematic person marker -t was used, added directly onto the verbal stem (formed by adding -s directly onto the root). That led to a complex word-final cluster, which was deleted entirely. In the prototonic form (after two proclitics), the root was unstressed and thus the root vowel was also deleted, leaving only the first consonant:

Examples of extreme allomorphy of 3rd person singular s-subjunctive, conjunct[23]
Present Indicative Present Subjunctive
Positive (Deuterotonic) Negative (Prototonic) Positive (Deuterotonic) Negative (Prototonic)
Primitive Irish Old Irish Primitive Irish Old Irish Primitive Irish Old Irish Primitive Irish Old Irish
"he refuses" *uss ˈbond-et(i) as·boind *nís ˈuss-bond-et(i) ní op(a)ind /obənʲdʲ/ *uss 'bod-s-t as·bó *nís ˈuss-bod-s-t ní op /ob/
"he remains over" *di ˈwo-uss-ret-et(i) do·fúarat *nís ˈdi-wo-uss-ret-et(i) ní díurat *di ˈwo-uss-ret-s-t do·fúair *nís ˈdi-wo-uss-ret-s-t ní diúair
"he repeats, amends" *ad ˈess-reg-et(i) ad·eirrig *nís ˈ*ad-ess-reg-et(i) (ní aithrig?? >) ní aithirrig *ad ˈess-reg-s-t ath·e(i)rr *nís ˈad-ess-reg-s-t ní aithir
"he can" *con ˈink-et(i) com·ic *nís ˈcom-ink-et(i) ní cum(a)ic > ní cum(u)ing, ní cumaing *con ˈink-s-t con·í *nís ˈcom-ink-s-t, *nís ˈcom-ink-ā-t ní cum, ní cumai
"it happens" *ad ˈcom-ink-et(i) (ad·cum(a)ic >) ad·cumaing *nís ˈad-com-ink-et(i) (ní ecm(a)ic >) ní ecmaing *ad ˈcom-ink-ā-t ad·cumai *nís ˈad-com-ink-ā-t ní ecm(a)i

Syncope in detail[edit]

In more detail, syncope of final and intervocalic syllables involved the following steps (in approximate order):

  • Shortening of absolutely final long vowels.
  • Loss of most final consonants, including *m, *n, *d, *t, *k, and all clusters involving *s (except *rs, *ls, where only the *s is lost).
  • Loss of absolutely final short vowels (including those that became final as a result of loss of a final consonant and original long final vowels).
  • Shortening of long vowels in unstressed syllables.
  • Collapsing of vowels in hiatus (producing new unstressed long vowels).
  • Syncope (deletion) of vowels in every other interior unstressed syllable following the stress. If there are two remaining syllables after the stress, the first one loses its vowel; if there are four remaining syllables after the stress, the first and third lose their vowel.
  • Resolution of impossible clusters resulting from syncope and final-vowel deletion:
    • Adjacent homorganic obstruents where either sound was a fricative became a geminate stop, voiceless if either sound was voiceless (e.g. *ðð * *ðd > /dd/; *θð *ðθ *θd * etc. > /tt/).
    • Otherwise, adjacent obstruents assumed the voicing of the second consonant (e.g. *dt > /tt/; *kd > /ɡd/; *ɣt > /xt/).
    • *l *r *n not adjacent to a vowel became syllabic and then had a vowel inserted before them (e.g. domun "world" < *domn < *domnos < *dumnos; immormus "sin" < *imm-ro-mess). However, in the case of *n, that occurred only when the nasal had not previously been joined to a following voiced stop as a result of nasal assimilation: compare frecnd(a)irc "present" (disyllabic).
    • Remaining impossible clusters were generally simplified by deletion of consonants not adjacent to vowels (such as between other consonants). However, Old Irish tolerated geminates adjacent to other consonants as well other quite complex clusters: ainm /aNʲm/ "name" (one syllable), fedb /fʲeðβ/ "widow", do-aidbdetar /do-ˈaðʲβʲðʲədər/ "they are shown".[24]

Proto-Celtic short vowels, vowel affection[edit]

All five Proto-Celtic short vowels (*a, *e, *i, *o, *u) survived into Primitive Irish more or less unchanged in stressed syllables.

During approximately A.D. 450-550 (just before the Old Irish period, c. 600-900), however, there occurred several vowel-changes (umlauts). Former vowels are modified in various ways depending on the following vowels (or sometimes surrounding consonants). The mutations are known in Celtic literature as affections or infections such as these, the most important ones:[25]

  1. i-affection: Short *e and *o are raised to i and u when the following syllable contains a high vowel (*i, *ī, *u, *ū). It does not happen when the vowels are separated by voiceless consonants or certain consonant groups.
  2. a-affection: Short *i and *u are lowered to e and o when the following syllable contains a non-high back vowel (*a, *ā, *o, *ō[clarification needed]).
  3. u-affection: Short *a, *e, *i are broken to short diphthongs au, eu, iu when the following syllable contains a *u or *ū that was later lost. It is assumed that at the point the change operated, u-vowels that were later lost were short *u while those that remain were long *ū. The change operates after i-affection so original *e may end up as iu.

Nominal examples (reconstructed forms are Primitive Irish unless otherwise indicated):

  • sen "old (nominative singular)" < *senos, but sin "old (genitive singular)" < *senī (i-affection), siun "old (dative singular)" < *senu (i-affection and u-affection) < *senū < PIE *senōi, sinu "old (accusative plural)" < *senūs (i-affection but no u-affection because u remains) < PIE *senons.
  • fer "man (nominative singular)" < Archaic Irish wiras (a-affection) < *wiros , but fir "man (genitive singular)" < *wirī (no a-affection), fiur "man (dative singular)" < *wiru (u-affection) < *wirū < PIE *wirōi, firu "men (accusative plural)" < *wirūs (no u-affection because the u remains) < PIE *wirons.
  • nert "strength (nominative singular)", but neurt "strength (dative singular)" < *nertu (u-affection but no i-affection, which was blocked by the cluster rt) < *nertū < PIE *nertōi.
  • mil "honey" (i-affection) < PCelt *meli, milis "sweet" < *melissos (i-affection).
  • fiurt "miracle (nominative singular)" < *wirtus (u-affection; from Latin virtus), fert(a)e "miracle (nominative plural)" < *wirtowes.

Before i-affection occurred, there was also a lowering of initial-syllable Proto-Celtic e to a before palatalized reflexes of *g, *gʷ, unless a /j/ followed them in the next syllable in Primitive Irish (no matter the /j/'s origin). For instance, Proto-Celtic *legeti-s "(s)he lies" vs. *legonti-s "they lie" led to Old Irish laigid and legait, respectively.

Verbal paradigm example:

form Pronunciation Meaning Prim Irish Post-PIE Comments
Absolute 1sg biru /bʲiru/ "I carry" *berūs *bʰerō + -s i-affection
Absolute 2sg biri /bʲirʲi/ "you (sg.) carry" *berisis *bʰeresi + -s i-affection (unstressed *-es- > *-is- in Primitive Irish, also found in s-stems)
Absolute 3sg beirid /bʲerʲəðʲ/ "he carries" *beretis *bʰereti + -s Unstressed i = /ə/ with surrounding palatalised consonants; see #Orthography
Conjunct 1sg ·biur /bʲĭŭr/ "I carry" *beru < *berū *bʰerō i-affection + u-affection
Conjunct 2sg bir /bʲirʲ/ "you (sg.) carry" *beris < *berisi *bʰeresi i-affection (unstressed *-es- > *-is- in Primitive Irish)
Conjunct 3sg beir /bʲerʲ/ "he carries" *beret < *bereti *bʰereti i in ei signals palatalisation of following consonant; see #Orthography

The result of i-affection and a-affection is that it is often impossible to distinguish whether the root vowel was originally *e or *i (sen < *senos and fer < *wiros have identical declensions). However, note the cases of nert vs. fiurt above for which i-affection, but not a-affection, was blocked by an intervening rt.

Short vowels before nasals and stops[edit]

Short vowels *a and *e regularly became e before nasals followed by originally voiceless stops, which then lengthened to é in stressed syllables.

  • cét "100" < *kantom and éc "death" < *ankus
  • sét "path, way" < *sentus

But a different development of *a occurred before nasals followed by voiced stops. Such *a became i when affected by i-affection and a when it was not. For example, land "land" is from Proto-Celtic *landā without i-affection but bind "melodious" is from *bandis with i-affection.[26]

Additionally, *a and *e were also raised to i when followed by a nasal, a voiced stop, and then either *e or a word-final *a followed by a nasal, despite those vowels not triggering i-affection.

  • imb "butter" < *amban
  • cing "he/she steps (conjunct)" < *kenget < *kengeti

Proto-Celtic long vowels and diphthongs[edit]

Proto-Celtic long vowels and diphthongs develop in stressed syllables as follows:

Proto-Celtic archaic Old Irish later Old Irish Example(s)
*ī í (gen. ríg) "king" (cf. Latin rēx, Sanskrit rājan-)
rím "number" (cf. Old English rīm, Latin rītus "rite")
*ā á máthir "mother" (cf. Latin māter)
dán "gift" (cf. Latin dōnum)
*ū ú cúl "back" (cf. Latin cūlus "ass, buttocks")
*ai /ai/ (spelled áe or ) merged (both spellings used) cáech "one-eyed" < PC *kaikos < PIE *keh₂i-ko- (cf. Latin caecus "blind", Gothic háihs "one-eyed")
*oi /oi/ (spelled óe or ) oín, óen "one" < PIE *oinos (cf. archaic Latin oenos)
*ei > ē é ía ·tíagat "they go" < archaic ·tégot < PIE *steigʰ- (cf. Ancient Greek steíkhein "to walk", Gothic steigan ‘to go up’)[27]
*au (+C)[* 3] > ō ó úa úaithed, úathad "singleness" < PC *autīto- < IE *h₂eu "again" + *to- "that" (cf. Ancient Greek autós "self")
*eu/ou (+C)[* 3] > ō núa, núë "new" < archaic núae < PC *noujos (cf. Gaulish novios) < IE *neu-io-s (cf. Gothic niujis)
túath "tribe, people" < PC *toutā < IE *teutā (cf. Gothic þiuda)
rúad "red" < PC *roudos < PIE *h₁reudʰ- (cf. Gothic rauþs)
*au (not +C)[* 4] áu ó ó "ear" < archaic áu, aue < PC *ausos < IE *h₂eus- (cf. Latin auris)
"ship" < archaic náu < PC *nāwā < PIE *neh₂u- (cf. Latin nāvis)
*ou (not +C)[* 4] óu > áu ‘cow’ < archaic báu < early archaic bóu (c. a.d. 700) < PC *bowos (gen.sg.) < PIE *gʷh₃-eu-

The Old Irish diphthongs úi, éu, íu stem from earlier sequences of short vowels separated by *w, e.g. drúid- "druid" < *dru-wid- "tree-knower".

Most instances of é and ó in nonarchaic Old Irish are due to compensatory lengthening of short vowels before lost consonants or to the merging of two short vowels in hiatus: cét /kʲeːd/ ‘hundred’ < Proto-Celtic kantom (cf. Welsh cant) < PIE *kṃtóm.

PIE consonants[edit]


See Proto-Celtic for various changes that occurred in all the Celtic languages, but these are the most important:

  • PIE * > Proto-Celtic *b (but PIE *gʷʰ > *).
  • Loss of aspiration in * * * *gʷʰ.
  • Loss of *p. Initially and intervocalically it was simply deleted; elsewhere, it variously became *w, *b, *x etc.

From Proto-Celtic to Old Irish, the most important changes are these:

  • Lenition and palatalisation, multiplying the entire set of consonants by 4. See #History for more details.
  • Loss of most final consonants. See #Syncope in detail.
  • Proto-Celtic *s is lenited to /h/, which then disappears between vowels. In general, Old Irish s when not word-initial stems from earlier geminate ss (often still written as such, especially in archaic sources).
  • Proto-Celtic * * remain in Ogam Irish (maqqi "son" (gen. sg.)) but become simple c g in Old Irish. Occasionally, they leave their mark by rounding the following vowel.
  • Proto-Celtic *w is lost early on between vowels, followed by early hiatus resolution. In some cases, *w combines with a preceding vowel to form a diphthong: béu béo "living, alive" < *bewas < *biwos < *gʷih₃uós.[28] Other instances of *w become [β], which still remains in Ogam Irish. By Old Irish times, this becomes f- initially (e.g. fer "man" < *wiros, flaith "lordship" < *wlātis), lenited b after lenited voiced sounds (e.g. tarb "bull" < *tarwos, fedb "widow" < *widwā), f after lenited *s (lenited fïur "sister" < *swesōr), and is lost otherwise (e.g. dáu "two" < *dwōu, unlenited sïur "sister" < *swesōr).
  • Proto-Celtic *y becomes *iy after a consonant, much as in Latin. The vowel *i often survives before a lost final vowel, partly indicating the nature of the final vowel as a result of vowel affection: cride cridi cridiu "heart" (nom. gen. dat.) < *kridion *kridiī *kridiū < *kridiyom *kridiyī *kridiyū < PIE *ḱr̥d- (e.g. gen. *ḱr̥d-és). After this, *y is lost everywhere (after palatalising a preceding consonant).

Initial clusters[edit]

Old Irish preserves, intact, most initial clusters unlike many other Indo-European languages.

Preserved initial clusters:[29]

  • sn- sm- sr- sl- sc- scr- scl-, e.g. snám "swimming", smiur "marrow", sruth "stream", scáth "shadow, reflection", scrissid "he scratches (out)", scléo "misery (?)".
  • cr- cl- cn-, e.g. crú "blood", cloth "fame", cnú "nut".
  • gr- gl- gn-, e.g. grían "sun", glé "clear", gnáth "customary".
  • tr- tl- tn-, e.g. tromm "heavy', tlacht "garment", tnúth "jealousy, passion".
  • dr- dl-, e.g. dringid "he climbs", dlong(a)id "he cleaves".
  • mr- ml-, e.g. mruig "land", mliuchtae "milch".
  • br- bl-, e.g. brú "belly", bláth "flower".

Modified initial clusters:[30]

  • *wl- *wr- > fl- fr-, e.g. flaith "lordship" < *wlātis, froích "heather" < *wroikos.
  • *sp-/*sw- > s- (lenited f-), e.g. sïur "sister" (lenited fïur) < *suior < PIE *swesōr.
  • *st- > s-, e.g. sál "heel" < *stātlā < *steh₂- "to stand"
    • But also irregularly > t-, e.g. tíagu "I go" < *stēgū-s < post-IE *steigʰō.
  • *pl- *pr- lose the *p.
  • PIE *gʷn- > Proto-Celtic *bn- > mn-, e.g. mná "woman" (gen. sg.) < *bnās < PIE *gʷneh₂s, an extremely archaic noun form.[* 5]


The rise of palatalized consonants arose in multiple stages.[14][31] In theories of palatalization, the front vowels are Proto-Celtic e, ē, i and ī.

The first palatalization affected single consonants and sequences of a nasal consonant followed by a homorganic voiced stop. The palatalization depended on not only the vowel after the consonant, but also the vowel before the consonant. The following Proto-Celtic vowel setups were eligible the first palatalization:

  • Any consonant followed by i or ī, with two main exceptions:
    • If the vowel before the consonant is ā and the sequence after is not -iy-.
    • If the consonant is not coronal and the vowel before it is a stressed rounded vowel.
  • A consonant entirely surrounded by any of the following vowels: e, ē, i, ī.

After the first palatalization, another palatalization ensued. Final-syllable Primitive Irish front vowels, after merging into a "palatal schwa", forced the palatalization of any consonants preceding them except the consonant cluster cht /xt/, which could never be palatalized. Greene labels this stage the second palatalization, while McCone treats this as a substage of the first palatalization.

The third palatalization entailed any front vowel in a second or fourth syllable of a Primitive Irish word causing the palatalization of the preceding consonants. Like with the final-syllable palatalization, these front vowels were generally assumed to merge into a palatalizing schwa before causing palatalization. After syncope regularly removed these vowels, the palatalization tended to spread across the resulting consonant cluster.

Dissimilatory deletion of lenited consonants[edit]

Lenited fricatives and /l/ straddling the boundary between a stressed syllable and an unstressed one tend to disappear if there is a homorganic consonant near the end of the next syllable. If a non-front vowel comes into contact with a front vowel after it due to this deletion, the two vowels fuse into a diphthong like or . Otherwise a hiatus between the two vowels may be formed instead.[32]

For the purposes of this sound law, /h/ is treated as if homorganic with s, due to its general origin in lenitions of Proto-Celtic *s.

Some examples of this sound law are given below:

  • deac, deec /de.əɡ/ "-teen" < *deǣg < *dexǣg < *dekank < *dekam-kʷe "and 10" (/x/ deleted before /ɡ/)
  • oíd /oið/ "lend!" < *oeðʲ < *oðeθʲ < *odete < *udete (/ð/ deleted before /θ/)
  • coímthecht /koimʲ.θʲext/ "company" < *koimbiθʲext < *koṽʲimbiθʲext < *kom-ambi-tixtā (lenited m deleted before non-leniting m)
  • foísam /foi.səṽ/ "protection" < *foisaṽ < *fohissaṽ < *uɸo-sistamus (lenited s deleted before another s)
  • for·roíchan /forˈRoixən/ "I taught" < *-rochechan < *-ɸro-kekana (/x/ deleted before another /x/)
  • ·fóelus /foilus/ "I will sustain (prototonic)" < *folilussū < *uɸo-liluxsū (/l/ deleted before another /l/)

This deletion and diphthong formation happened before syncope.[31] As a demonstration, coímthecht ended up syncopating its etymon's third syllable instead of the usual second. This can be explained by the first and second syllables fusing into one syllable due to dissimilatory deletion, making the etymon's third syllable the second syllable at the time of syncope.

Intervocalic clusters[edit]

Many intervocalic clusters are reduced, becoming either a geminate consonant or a simple consonant with compensatory lengthening of the previous vowel. During the Old Irish period, geminates are reduced to simple consonants, occurring earliest when adjacent to a consonant. By the end of the Old Irish period, written ll mm nn rr are repurposed to indicate the non-lenited sounds /L m N R/ when occurring after a vowel and not before a consonant.

Cluster reduction involving *n:

  • *nt *nk > unlenited /d ɡ/ (normally written t c). Note that PCelt *ant,*ent > *ent > /eːd/ but *int *ont *unt > /idd odd udd/ like *nk: cét /kʲeːd/ "hundred" < PCelt *kantom (cf. Welsh cant) < PIE *kṃtóm; sét /sʲeːd/ "way" < *sentu- (vs. Breton hent); ro·icc, ric(c) /r(o)-iɡɡ/ "he reaches" < *ro-ink- (vs. Bret rankout "must, owe"); tocad /toɡað/ "luck" (vs. Bret tonkad "fate").[33]
  • *ns > unlenited s with compensatory lengthening of a preceding vowel; *ans > *ens > és similarly to *ant *ank: géis "swan" < PCelt *gansi- < PIE *ǵʰh₂ens- (vs. Dutch gans "goose").

Cluster reduction involving *s *z:

  • Medial *sm *sn *sl > mm nn ll: am(m) "I am" < PIE *esmi.
  • Medially, *st > ss (but *str > str, *rst > rt).
  • *zb > db /ðb/, *zg > dg /ðɡ/ (but rg after an unstressed syllable), *zd > /dd/: net /nedd/ "nest" < PIE *nisdos /nizdos/.

Lenited stops *x *ɣ *θ *ð generally disappear before sonorants *r *l *n *m, with compensatory lengthening of the preceding vowel. Many examples occur in reduplicated preterites or words with consonant-final prefixes (such as ad-):[10]

  • du·air-chér "I have purchased" < *-xexr < PCelt *-kikra;
  • ·cúal(a)e "he heard" < *koxlowe < PCelt *kuklowe;
  • áram "number" < *að-rīm;
  • ám thám "a moving to and fro" < *aɣm θ-aɣm (verbal nouns of agid "he drives" and compound do·aig);
  • dál "assembly" < *daθl (cf. Old Welsh datl).

However, *θr, *βr, *βl survive: críathraid "he perforates" < PCelt *krētrāti-s; gabur "goat" < PCelt *gabros (cf. Welsh gafr); mebul "shame" < PCelt *meblā (cf. Welsh mefl).

Destruction of final syllables[edit]

Proto-Celtic final syllables were often reduced or deleted by Old Irish times. McCone envisions the evolution of final syllables as follows.[31]

Proto-Celtic unstressed long vowels were shortened unless protected by a following Primitive Irish final *-h, whether that *-h came from a final -s (as in several nominal inflectional endings) or -ti (as in 3rd-person singular present forms of verbs). These shortened long vowels included the feminine ā-stem nominative singular ending *-ā and the masculine and neuter o-stem ending *-ī.

Then, absolutely word-final -h, vowels, and nasals caused initial mutations if possible, possibly by resegmentation onto the following word. Any remaining final-syllable short vowels, -h, and nasals after this stage are deleted, while remaining final long vowels remained. It is also apparent in Ogham inscriptions that final-syllable Proto-Celtic *o had become *a by Primitive Irish before its loss.

In the following table, the cover symbol C refers to any consonant.

Evolution of pre-Old Irish final syllables
Proto-Celtic ending Pre-Irish stages Old Irish outcome Function
-Cos -Cah (no mutation) -C nominative singular ending of masculine o-stems and neuter s-stems, genitive singular ending of consonant stems
-Com -Can (triggers nasalization) -C nominative and accusative singular ending of neuter o-stems, accusative singular of masculine o-stems, genitive plural for all declension classes
-Cā -Ca (with shortening, triggers lenition) -C nominative singular ending of feminine ā-stems
-Cās -Cāh (without shortening) -Ca nominative plural of feminine ā-stems
-Cams -Cās > -Cāh (without shortening) -Ca accusative plural of consonant stems
-Cāti -Cāt (special loss of final -i in verbs) > -Cāθ > -Cāh (without shortening) -Ca conjunct 3rd-person singular ending for the presents of A I verbs
-Cai -Cī > -Ci (with shortening, triggers lenition) -Cʲ dative singular of ā-stems
-Cis -Cih -Cʲ nominative singular for i-stems
-Cīs -Cīh (without shortening) -C(ʲ)i nominative plural for i-stems
-Cī -Ci (with shortening) -Cʲ genitive singular ending of o-stems, nominative plural of masculine o-stems, nominative singular of feminine ī-stems
-Cūs -Cūh (without shortening) -Cu accusative plural ending for masculine o-stems
-Cūi -Cū > -Cu (with shortening, triggers lenition) -(u)C dative singular for o-stems
-Cus -Cuh -(u)C nominative singular for u-stems
-Cous -Cōs > -ōh (without shortening, no mutation) -Co genitive singular ending of u-stems


Old Irish is a fusional, nominative-accusative, and VSO language.

Nouns decline for 5 cases: nominative, accusative, genitive, prepositional, vocative; 3 genders: masculine, feminine, neuter; 3 numbers: singular, dual, plural. Adjectives agree with nouns in case, gender, and number. The prepositional case is called the dative by convention.

Verbs conjugate for 3 tenses: past, present, future; 3 aspects: simple, perfective, imperfective; 4 moods: indicative, subjunctive, conditional, imperative; 2 voices: active, and passive; independent, and dependent forms; and simple, and complex forms. Verbs display tense, aspect, mood, voice, and sometimes portmanteau forms through suffixes, or stem vowel changes for the former four. Proclitics form a verbal complex with the core verb, and the verbal complex is often preceded by preverbal particles such as (negative marker), in (interrogative marker), ro (perfective marker). Direct object personal pronouns are infixed between the preverb and the verbal stem. Verbs agree with their subject in person and number. A single verb can stand as an entire sentence. Emphatic particles such as -sa and -se are affixed to the end of the verb.

Prepositions inflect for person and number, and different prepositions govern different cases, sometimes depending on the semantics intended.

See also[edit]


  1. ^ It is difficult to know for sure, given how little Primitive Irish is attested and the limitations of the Ogham alphabet used to write it.
  2. ^ a b c d
    • ingen /inʲɣʲən/ "daughter" < Ogam inigena < Proto-Celtic *eni-genā (cf. Latin indigenā "(female) native", Ancient Greek engónē "granddaughter").
    • ingen /iNʲɡʲən/ "claw, nail" < Proto-Celtic *angʷīnā < PIE *h₃n̥gʷʰ- (cf. Latin unguis).
  3. ^ a b When followed by a consonant in Old Irish.
  4. ^ a b When not followed by a consonant in Old Irish. This includes words originally followed by *s, which was lost by Old Irish times.
  5. ^ Originally a neuter proterokinetic noun of the form *gʷenh₂ (nom. sg.), *gʷneh₂s (gen. sg.). The original PIE nominative is still preserved in poetic or legal Old Irish N "woman" (still neuter!) < Proto-Celtic *ben < PIE *gʷenh₂. The normal Old Irish nominative is benL (feminine) < Proto-Celtic *benā < *ben + normal feminine *-ā. No other IE language preserves the original neuter gender.


  1. ^ "CE3063: Introduction to Old Gaelic 1A - Catalogue of Courses".
  2. ^ a b Koch, John Thomas (2006). Celtic culture: a historical encyclopedia. ABC-CLIO. p. 831. The Old Irish of the period c. 600–c. 900 AD is as yet virtually devoid of dialect differences, and may be treated as the common ancestor of the Irish, Scottish Gaelic, and Manx of the Middle Ages and modern period; Old Irish is thus sometimes called 'Old Gaelic' to avoid confusion.
  3. ^ Ó Baoill, Colm (1997). "13: The Scots-Gaelic Interface". The Edinburgh History of the Scots Language. Edinburgh University Press. p. 551. The oldest form of the standard that we have is the language of the period c. AD 600–900, usually called 'Old Irish' – but this use of the word 'Irish' is a misapplication (popular among English-speakers in both Ireland and Scotland), for that period of the language would be more accurately called 'Old Gaelic'.
  4. ^ Jaskuła 2006.
  5. ^ Bo (27 September 2008). "THE CANTOS OF MVTABILITIE: The Old Irish Verbal System". THE CANTOS OF MVTABILITIE. Archived from the original on 25 October 2018. Retrieved 25 October 2018.
  6. ^ Thurneysen 1946, p. 4.
  7. ^ Stifter, David (1998). "Old Irish ²fén 'bog'?" Die Sprache 40(2), pp. 226-228.
  8. ^ Qiu, Fangzhe (2019). "Old Irish aue ‘descendant’ and its descendants". Indogermanische Forschungen 124(1), pp. 343–374
  9. ^ Kortlandt 2007, p. 8.
  10. ^ a b Thurneysen 1946, p. 79.
  11. ^ Thurneysen 1946, p. 32.
  12. ^ a b c d Dennis King. "Old-Irish Spelling and Pronunciation." Sabhal Mòr Ostaig, 11 Dec 1998, http://www.smo.uhi.ac.uk/sengoidelc/donncha/labhairt.html Archived 30 July 2019 at the Wayback Machine.
  13. ^ Kortlandt 2007.
  14. ^ a b Greene 1973.
  15. ^ Thurneysen 1946, p. 18.
  16. ^ Thurneysen 1946, p. 137.
  17. ^ Thurneysen 1946, p. 181.
  18. ^ Thurneysen 1946, p. 58.
  19. ^ Thurneysen 1946, p. 98.
  20. ^ Thurneysen 1946, pp. 192–193.
  21. ^ Thurneysen 1946, p. 42.
  22. ^ Thurneysen 1946, p. 68.
  23. ^ Fortson 2004, p. 324.
  24. ^ Thurneysen 1946, pp. 70, 100.
  25. ^ Thurneysen 1946, pp. 46–50, 57.
  26. ^ Schrijver, Peter (1991). "The Development of Primitive Irish aN before Voiced Stop". Ériu. Royal Irish Academy. 42: 13–25. JSTOR 30007533. Retrieved 31 May 2022.
  27. ^ Thurneysen 1946, p. 36.
  28. ^ Thurneysen 1946, p. 125.
  29. ^ Thurneysen 1946, pp. 128–140.
  30. ^ Thurneysen 1946, pp. 123–139.
  31. ^ a b c McCone, K. (1996). Towards a Relative Chronology of Ancient and Medieval Celtic Sound Change. Maynooth studies in Celtic linguistics. Maynooth: Department of Old Irish, St. Patrick's College. ISBN 978-0-901519-40-5.
  32. ^ Schrijver, Peter (1993). "Varia IV. OIr. dëec, dëac". Ériu. Royal Irish Academy. 44: 181–184. ISSN 2009-0056. JSTOR 30006888. Retrieved 25 June 2022.
  33. ^ Thurneysen 1946, pp. 126–127.


External links[edit]