|Majuscule forms (also called uppercase or capital letters)|
|Minuscule forms (also called lowercase or small letters)|
The letter j is accepted in Welsh orthography for those words borrowed from English in which the /dʒ/ sound is retained in Welsh, even where that sound is not represented by j in English spelling, as in garej (for garage). Some borrowed words that are spelt with a j in English may be pronounced with either /dʒ/ or /ʃ/ in Welsh; the latter pronunciation is represented by si, as in Siapan for Japan.
The letters k, v, x and z are used in some technical terms, like kilogram, volt, xeroser and zero, but in all cases can be, and often are, replaced by Welsh letters: cilogram, folt, seroser and sero. Nevertheless, in the Welsh colony in Patagonia, v is used generally to represent the sound /v/.
The earliest samples of written Welsh date from the 6th century and are in the Latin alphabet (see Old Welsh). The orthography differs from that of modern Welsh particularly in the use of p, t and c to represent the voiced plosives /b, d, ɡ/ in the middle and at the end of words. Similarly, the voiced fricatives /v, ð/ were written with b and d.
By the Middle Welsh period, this had given way to much variability: although b, d and g were now used to represent /b, d, ɡ/, these sounds were also often written as in Old Welsh, while /v/ could be denoted by u, v, f or w. In earlier manuscripts, moreover, fricatives were often not distinguished from plosives (e.g. t for /θ/, the sound now written with th). The grapheme k was also used more commonly than in the modern alphabet, particularly before front vowels. The disuse of this letter is at least partly due to the publication of William Morgan's Welsh Bible, whose English printers, with type letter frequencies set for English and Latin, did not have enough k letters in their type cases to spell every /k/ sound as k, so the order went "C for K, because the printers have not so many as the Welsh requireth"; this was not liked at the time, but has become standard usage.
In 1928 a committee chaired by Sir John Morris-Jones standardised the orthography of modern Welsh.
In 1987, a committee chaired by Professor Stephen J. Williams made further small changes. The conventions established by these committees are not adhered to by all modern writers.
Letter names and sound values 
"N" and "S" represent the variants in the northern and southern dialects of Welsh.
Letter Name Corresponding sounds English approximation a â /a, ɑː/ cat (short) / father (long) b bî /b/ bat c èc /k/ case ch èch /χ/ loch (Scottish) d[* 1] dî /d/ day dd èdd /ð/ this e ê /ɛ, eː/ bed (short) / closest to hey (long) f èf /v/ vat ff èff /f/ four g èg /ɡ/ gate ng èng /ŋ/ thing h[* 2] âets, hâ /h/ hat i î (N), î dot (S) /ɪ, iː, j/ bit (short) / machine (long) / yes (as consonant; before vowels) l èl /l/ lad ll ell /ɬ/ not present in English; a voiceless alveolar lateral fricative m èm /m/ mat n en /n/ net o ô /ɔ, oː/ Short, like "bog" in RP; long like stove in Scottish English, North Central American English and West/Central Canadian English p pî /p/ pet ph ffî /f/ phone r èr /r/ rat (trilled) rh rhî, rhô /r̥/ pray (trilled): an unvoiced [r] s[* 1] ès /s/ sat t[* 1] tî /t/ tan th èth /θ/ thin u û (N), û bedol (S) /ɨ̞, ɨː/ (N), /ɪ, iː/ (S) for Southern variants: bit (short) / machine (long); /ɨ̞, ɨː/ not found in English. w ŵ /ʊ, uː, w/ book (short) / pool (long) / wet (as consonant) y[* 3] ŷ /ɨ̞, ɨː, ə/ (N)
/ɪ, iː, ə, əː/ (S)
for Southern variants: bit (final syllable, short) / machine (final syllable, long)
above (other places, short) / roses /ɨ̞, ɨː/, found in certain dialects of English that differentiate "Rosa's" and "roses", for example, General American.
- The sequence si indicates /ʃ/ when followed by a vowel; similarly, di and ti sometimes indicate /dʒ/ and /tʃ/ respectively when followed by a vowel, although these sounds are spelled j and ts in loanwords like jẁg "jug" and wats "watch".
- In addition to representing the phoneme /h/, h indicates voicelessness in the graphemes mh, nh, and ngh. The digraph ph – which indicates the aspirate mutation of p (e.g. ei phen-ôl) – may also be found very occasionally in words derived from Greek (e.g. phenol), although most words of Greek origin are spelt with ff (e.g. ffotograff).
- The vowel letter y indicates /ə/ in unstressed monosyllabic words (e.g. y "the", fy "my") or non-final syllables (regardless of whether these are stressed or not), but /ɨ̞, ɨː/ (N) or /ɪ, iː/ (S) in word-final syllables (again, regardless of stress).
Orthography Northern dialects Southern dialects English (approximation only) ae /ɑːɨ/ /ai/ eye ai /ai/ /ai/ eye au /aɨ/ but as plural ending /a/ /ai/ but as plural ending /e/ eye / bet (plural ending) aw /au, ɑːu/ /au/ how ei /əi/ /əi/ Like "write" in Canadian English eu /əɨ/ /əi/ Like "write" in Canadian English ew /ɛu, eːu/ /ɛu/ Roughly like wayward ey /əɨ/ /əi/ Like "write" in Canadian English iw /ɪu/ /ɪu/ not present in English except in the interjection Ew!; closest to 'i-oo' (short i) oe /ɔɨ, ɔːɨ/ /ɔi/ boy oi /ɔi/ /ɔi/ boy ou /ɔɨ, ɔːɨ/ /ɔi/ boy uw /ɨu/ /ɪu/ not present in English; closest to 'i-oo' (short i) wy /ʊɨ, uːɨ/ /ʊi/ not present in English; closest to gooey yw /ɨu, əu/ /ɪu, əu/ /ɪu/ not present in English; closest to 'i-oo' (short i)
/əu/ like "goat" in Received Pronunciation or like "house" in Canadian English
Welsh makes use of a number of diacritics.
The circumflex (ˆ) is used to mark long vowels, so â, ê, î, ô, û, ŵ, ŷ are always long. However, not all long vowels are marked with a circumflex, so the letters a, e, i, o, u, w, y with no circumflex do not necessarily represent short vowels; see "Predicting vowel length from orthography" below.
The grave accent (`) is sometimes used to mark vowels that are short when a long vowel would normally be expected, e.g. pas /pɑːs/ (a cough), pàs /pas/ (a pass/permit or a lift in a car); mwg /muːɡ/ (smoke), mẁg /mʊɡ/ (a mug).
The acute accent (´) is sometimes used to mark a stressed final syllable in a polysyllabic word. Thus the words gwacáu (to empty) and dicléin (decline) have final stress. However, not all polysyllabic words with final stress are marked with the acute accent (Cymraeg "Welsh", for example, is written with none). The acute may also be used to indicate that a letter w represents a vowel where a glide might otherwise be expected, e.g. gẃraidd /ˈɡʊ.raið/ (two syllables) "manly", as opposed to gwraidd /ˈɡwraið/ (one syllable) "root". Similarly, the diaeresis (¨) is used to indicate that two adjoining vowels are to be pronounced separately, e.g. copïo (to copy) pronounced /kɔˈpiːɔ/, not */ˈkɔpjɔ/.
The grave and acute accents in particular are very often omitted in casual writing, and the same is true to a lesser extent of the diaeresis. The circumflex, however, is usually included. Accented vowels are not considered distinct letters.
Predicting vowel length from orthography 
As mentioned above, vowels marked with the circumflex are always long, and those marked with the grave accent are always short. If a vowel is not marked with a diacritic, its length must be determined by its environment; the rules vary a bit according to dialect.
In all dialects, only stressed vowels may be long; unstressed vowels are always short.
An unmarked (stressed) vowel is long:
- in the last syllable of a word when no consonant follows, e.g. da /dɑː/ (good)
- before b, ch, d, dd, g, f, ff, th, e.g. mab /mɑːb/ (son), hoff /hoːf/ (favourite), peth /peːθ/ (thing)
- before word-final s, e.g. nos /noːs/ (night)
An unmarked vowel is short:
- in an unstressed (proclitic) word, e.g. a /a/ (and)
- before p, t, c, ng, e.g. iet /jɛt/ (gate), lloc /ɬɔk/ (sheepfold), llong /ɬɔŋ/ (ship)
- before most consonant clusters, e.g. sant /sant/ (saint), perth /pɛrθ/ (hedge), Ebrill /ˈɛbrɪɬ/
The vowel y, when it is pronounced /ə/, is always short, even when it appears in an environment where other vowels would be long, e.g. cyfan (whole) /ˈkəvan/. When pronounced as a close or near-close vowel (/ɨ/ or /ɨ̞/ in the North, /i/ or /ɪ/ in the South), y follows the same rules as other vowels, e.g. dydd (day) /ˈdɨːð/ (North) ~ /ˈdiːð/ (South), gwynt (wind) /ˈɡwɨ̞nt/ (North) ~ /ˈɡwɪnt/ (South).
Before l, m, n, and r, unmarked vowels are long in some words and short in others, e.g. gwin /ɡwiːn/ (wine), prin /prɪn/ (scarcely); hen /heːn/ (old), pen /pɛn/ (head); dyn /dɨːn/ ~ /diːn/ (man), gwyn /ɡwɨ̞n/ ~ /ɡwɪn/ (white); stwmo /ˈstuːmo/ (bank up a fire), amal /ˈamal/ (often); celyn /ˈkeːlɪn/ (holly), calon /ˈkalɔn/ (heart). (The last four examples are given in South Welsh pronunciation only, since vowels in nonfinal syllables are always short in North Welsh.) Before nn and rr, vowels are always short, e.g. onn /ˈɔn/ (ash trees), ennill /ˈɛnɪɬ/ (to win), carreg /ˈkarɛɡ/ (stone).
In Northern dialects, long vowels must not only be stressed, they must also appear in the final syllable of the word. Vowels in non-final syllables are always short. In addition to the rules above, a vowel is long in the North before a consonant cluster beginning with s, e.g. tyst /tɨːst/ (witness). Before ll, a vowel is short when no consonant follows the ll, e.g. gwell (better) /ɡwɛɬ/, but long when another consonant does follow the ll, e.g. gwallt /ɡwɑːɬt/ (hair).
In Southern dialects, long vowels may appear in a stressed penultimate syllable as well as in a stressed word-final syllable. Before ll, a stressed vowel in the last syllable is long, e.g. gwell (better) /ɡweːɬ/. However, a stressed vowel in the penult before ll is short, e.g. dillad /ˈdɪɬad/ (clothes). Before s, a stressed vowel in the last syllable is long, as mentioned above, but a stressed vowel in the penult is short, e.g. mesur (measure) /ˈmɛsir/. Vowels are always short before consonant clusters, e.g. sant /sant/ (saint), gwallt /ɡwaɬt/ (hair), tyst /tɪst/ (witness).
While the digraphs ch, dd, ff, ng, ll, ph, rh, th are each written with two symbols, they are all considered to be single letters. This means, for example that Llanelli (a town in South Wales) is considered to have only six letters in Welsh, compared to eight letters in English. Consequently, they each take up only a single space in Welsh crosswords.
Sorting is done in correspondence with the alphabet. For example, la comes before ly, which comes before lla, which comes before ma. Automated sorting may occasionally be complicated by the fact that additional information may be needed to distinguish a genuine digraph from a juxtaposition of letters; for example llom comes after llong (in which the ng stands for /ŋ/) but before llongyfarch (in which n and g are pronounced separately as /ŋɡ/).
Although the digraphs above are considered to be single letters, only their first component letter is capitalised when a word in lower case requires an initial capital letter. Thus:
- Llandudno, Ffestiniog, Rhuthun, etc. (place names)
- Llŷr, Rhian, etc. (personal names)
- Rhedeg busnes dw i. Llyfrgellydd ydy hi. (other sentences starting with a digraph)
The two letters in a digraph are capitalised only when the whole word is in uppercase:
- LLANDUDNO, LLANELLI (as on a poster or sign)
See also 
- Thomas, Peter Wynn (1996) Gramadeg y Gymraeg. Cardiff: University of Wales Press: 757.
- Watkins, T. Arwyn (1993) "Welsh" in Ball, Martin J. with Fife, James (Eds) The Celtic Languages. London/New York: Routledge: 289-348.
- Evans, Simon D. (1964) A Grammar of Middle Welsh. Dublin: ColourBooks Ltd.
- English and Welsh, an essay by J. R. R. Tolkien
- Thomas, Peter Wynn (1996) Gramadeg y Gymraeg. Cardiff: University of Wales Press: 749.
- Awbery, Gwenllian M. (1984). "Phonotactic constraints in Welsh". In Ball, Martin J.; Jones, Glyn E. Welsh Phonology: Selected Readings. Cardiff: University of Wales Press. pp. 65–104. ISBN 0-7083-0861-9.
- Morris Jones, J. (1913). A Welsh Grammar, Historical and Comparative. Oxford: Clarendon Press. pp. 11–18, 65–74.
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