# Numeral prefix

(Redirected from Tri-)
"semi-" redirects here. For other uses, see semi (disambiguation).

Numeral or number prefixes are prefixes derived from numerals or occasionally other numbers. In English and other European languages, they are used to coin numerous series of words, such as unicycle – bicycle – tricycle, dyad – triad – decade, biped – quadruped, September – October – November – December, decimal – hexadecimal, sexagenarian – octogenarian, centipede – millipede, etc. There are two principal systems, taken from Latin and Greek, each with several subsystems; in addition, Sanskrit occupies a marginal position.[1] There is also an international set of metric prefixes, which are used in the metric system, and which for the most part are either distorted from the forms below or not based on actual number words.

## Table of number prefixes in English

In the following prefixes, a final vowel is normally dropped before a root that begins with a vowel, with the exceptions of bi-, which is bis- before a vowel, and of the other monosyllables, du-, di-, dvi-, tri-, which are invariable.

The cardinal series are derived from cardinal numbers, such as the English one, two, three. The multiple series are based on adverbial numbers like the English once, twice, thrice. The distributives originally meant one each, two each or one by one, two by two, etc., though that meaning is now frequently lost. The ordinal series is based on ordinal numbers such as the English first, second, third. For numbers higher than 2, the ordinal forms are also used for fractions; only the fraction ½ has special forms.

For the hundreds, there are competing forms: those in -gent-, from the original Latin, and those in -cent-, derived from centi- etc. plus the prefixes for 1–9.

Number Latin prefixes Greek prefixes** Sanskrit[1]
Cardinal Multiple Distributive Ordinal Cardinal Multiple
Proportional
Quantitative
Ordinal
0 nulli-  – meden-, ouden-  –
⅟₁₂ unci-  – For the fractions Greeks were using the ordinals (i.e. dodecato-)  –
octant-  –  –  – As above; ogdoö  –
sextant-  –  –  – As above; hecto–  –
¼ quadrant-  –  –  – As above; tetarto–  –
trient-  –  –  – As above; trito–  –
½ semi-  – demi-[2]  – hemi- (mn. half)
e.g. hemisphere
–  –
¾ dodrant-  –  –  –  –  –
1 uni- e.g.
universe, unilateral
sim-[3] singul- prim- mono-
"one", "alone"
e.g. monogamy
holo-
(entire/full)
e.g. holocaust, holography
hen-[4]
rare
mono- ("one, alone")
hapax- ("once")
haplo-[4] (single)
monad- ("one of a
kind/unique/unit")
prot-[5]
e.g. proton, protozoa
eka-
quasqui-
sesqui-
2 du- bi-, bis-
bireme, bilingual,
bipolar, bipartisan
bin- second- di-, dy-,[6] duo-,
dyo-
dis-[7] ("twice") common
dyakis- ("twice") rare
diplo- ("double")
dyad- (two of a
kind)
deuter-[8]
e.g. Deuteron/ium
Deuteronomy
deuteraio-
([every] second day)
dvi-
3 tri-
e.g. trireme
ter- tern-, trin- terti- tri-
e.g. triathlon,
Tripolis
tris-[9] ("thrice") common
triakis- ("thrice") rare
triplo- ("triple")
triad- (three of a
kind)
trit-[10] ("third")
e.g. Triton/ium
tritaio- ([every]
third day
tri-
quater-[12] quatern-[13] quart-[14] tetra-,
tessara-
tetrakis-
(four times)
tetrad- (four of a
kind)

ie. tetrahedron
tetarto- (fourth)
tetartaio-
([every] fourth day)
chatur-
5 quinque-[15]  – quin-[16] quint-[17] penta- pentakis-
pentaplo-
e.g. pentahedron
pempt-[18]
pemptaio-
pancha-
6 sexa-[19]  – sen-[20] sext-[21] hex-[22] hexakis-
hexaplo-
e.g. hexahedron
hect-[23]
hectaio-
shat-
7 septem-,
septi-
septen-[24] septim- hepta-[25]
e.g. heptathlon
heptakis-
heptaplo-
hebdomo- (7th)
hebdomaio-
("seventh day")
hebdomas ("week")
sapta-
8 octo-
e.g. October
– octon-[26] octav-[27] octo-
e.g. octopus
octakis-
octaplo-
e.g. octahedron
ogdoö-
ogdoaio-
ashta-
9 novem-
e.g. November
noven- nona- ennea-[28] enneakis-
enneaplo-
enat-[29]
enataio-
navam-
10 decem-, dec- den-[30] decim-[31] deca-[32]
e.g. decathlon,
Decapolis
deca/kis/plo/d-
e.g. decahedron,
decagon
decat-[33]
decataio-
dasham-
11 undec- unden-[34] undecim-[35] hendeca-[36] hendeca/kis/plo/d- hendecat-[37]/o/aio- ekadasham-
12 duodec- duoden-
ie. duodenum
duodecim- dodeca-[38] e.g.
dodeca/kis/plo/d-
e.g. dodecahedron
13 tredec- treden- tredecim- tria(kai)deca-,
decatria- ie.
triakaidekaphobia
tris(kai)decakis-,
decatria/kis/plo/d-
decatotrito-
etc.
trayodasham-
14 quattuordec- quattuorden- quattuordecim- tessara(kai)deca-,
decatettara,
decatessara-
tetra(kai)decakis-,
decatetra/kis/plo/d-
decatetrahedron
decatotetarto- chaturdasham-
15 quinquadec-, quindec-[40] quinden-[41] quindecim-[42] pente(kai)deca-,
decapente-
penta(kai)decakis-,
decapentakis- etc.
16 sedec-,[43]
sexdec- (but hybrid hexadecimal[19])
seden- sedecim- hexa(kai)deca-,
hekkaideca-,
decahex-
hexa(kai)decakis-,
decahexakis- etc.
decatohecto- shodasham-
17 septendec- septenden- septendecim- hepta(kai)deca-,
decahepta-
hepta(kai)decakis-,
decaheptakis- etc.
18 octodec- octoden- octodecim- octo(kai)deca-,
decaocto-
octa(kai)decakis-,
decaoctakis- etc.
19 novemdec-,
novendec-
novemden- novemdecim- ennea(kai)deca-,
decaennea-
ennea(kai)decakis-,
decaenneakis- etc.
20* viginti- vicen-,
vigen-
vigesim- (e)icosi- eicosa/kis/plo/d-
ie. (e)icosahedron
eicosto- vimshati-
22 duovigint- (e)icosidyo-,
dyo(e)icosi- rare
ie. docosa-hexaenoic acid
a pejoration of dyoicosa-hexanoic
(e)icosidyakis-
(e)icosidiplo-
eicostodeutero-
24 quattuorvigint- (e)icositettara-,
(e)icosikaitettara-
rare
(e)icositetrakis-
(e)icositetraplo-
ie. (e)icositetragon
eicostotetarto- chaturvimshati-
25 quinvigint- (e)icosipente- ie.
eicosapenta-enoic acid
(e)icosipentakis-
(e)icosipentaplo-
eicostopempto-
30 triginti- tricen- trigesim- triaconta- triacontakis- etc.
ie. triacontahedron
triacosto- trimshat-
31 untriginti- triacontahen- triacontahenakis-
triacontahenaplo-
triacostoproto-
triacostoprotaio-
tessaraconta-
tettaracontakis-,
tessaracontakis- etc.
tessaracosto- chatvarimshat-
50 quinquaginti-[44] quinquagen-[45] quinquagesim-[46] penteconta-
ie. penteconter
pentecontakis- etc. pentecosto-
ie. pentecost
panchashat-
60 sexaginti- sexagen- sexagesim- hexeconta- hexecontakis- etc. hexecosto- shasti-
70 septuaginti-
ie. Septuagint
septuagen- septuagesima- hebdomeconta- hebdomecontakis- etc. hebdomecosto- saptati-
80 octogint- octogen- octogesim- ogdoëconta- ogdoëcontakis- etc. ogdoëcosto- ashiti-
90 nonagint- nonagen- nonagesim- eneneconta- enenecontakis- etc. enenecosto- navati-
100 centi- centen- centesim- hecato(n)- hecatontakis-
hundred times
hecatontaplo-
hundred-multiple
hundred of a kind
also abbreviated in
hecatosto-
hundredth
hecatostaio-
the hundredth day
shata–
120 viginticenti-     hecaton(e)icosi- hecaton(e)icosakis- etc. hecatostoeicosto-
200 ducenti- ducen-,
bicenten-
ducentesim- diacosia- diacosakis- etc. diacosiosto-  –
300 trecenti- trecen-,
tercenten-,
tricenten-
trecentesim- triacosia- etc. triacosakis-
triacosaplo-
triacosiosto-  –
quatercenten-,
quadringentesim- tetracosia- tetracosakis- etc. tetracosiosto-
500 quingent-,[47]
quincent-[48]
quingen-,[49]
quingenten-,
quincenten-
quingentesim-[50] pentacosia- pentacosakis- etc. pentacosiosto-
600 sescenti-, sexcenti- sescen-,
sexcenten-
sescentesim- hexacosia- hexacosakis- etc. hexacosiosto-
700 septingenti- septingen-,
septingenten-,
septcenten-
septingentesim- heptacosia- heptacosakis- etc. heptacosiosto-
800 octingenti- octingen-,
octingenten-,
octocenten-
octingentesim- octacosia- octacosakis- etc. octacosiosto-  –
900 nongenti- nongen- nongentesim- ennacosi-[51]
derived from
en(n)iacosia-,
a pejoration of
enneacosia-
enneacosakis- etc. enacosiost-,[52]
alt. spelling
en(n)iacosiost(o)-
a pejoration of
enneacosiosto-
–
1000 milli- millen- millesim- chili-,[53]
kilo-
chiliakis-
chiliaplo-
chiliost-[54] sahasra–
2000 dumilli-  –-  - dischili-[55] dischiliakis- etc. dischiliosto-  –
3000 trimilli– trischili-[56] trischiliost-[57]  –
5000 quinmilli– pentacischili-[58]
10000 decamilli– myria-,[59]
e.g. myriapoda
decakischilia-
myriakis-
myriaplo-
decakischiliakis- etc.
myriast-,[60]
decakischiliosto-
ayuta–
80000 octogintmilli– octacismyri-[61]
105 centimilli;– decakismyria-,
hecatontakis
chilia-
decakismyriakis-,
hecatontakis
chiliakis-
etc.
106 million-  – hecatommyria- hecatommyriakis-
("a million times")
hecatommyriaplo-
(million-multiple)
(a million of a kind)
hecatommyriosto-
(ranked millionth;
also one piece of
a million [fraction] see above in
fractions)

hecatommyriostaio-
("the millionth day")
109 billion-  – dis
hecatommyria-
dis
hecatommyriakis-
etc.
1012 trillion-  – tris
hecatommyria-
tris
hecatommyriakis-
etc.
1015 quadrillion-  – tetrakis
hecatommyria-
tetrakis
hecatommyriakis-
etc.
1033 decillion-  – decakis
hecatommyria-
decakis
hecatommyriakis-
etc.
10303 centillion-  – hecatontakis
hecatommyria-
hecatontakis
hecatommyriakis-
etc.
103003  – chiliakis
hecatommyria-
chiliakis
hecatommyriakis-
etc.
1030003  – myriakis
hecatommyria-
myriakis
hecatommyriakis-
etc.
10300003  – decakismyriakis
hecatommyria- and so on -
virtually endless
decakismyriakis
hecatommyriakis-
etc.
Many
(> 1)
multi-
ie. multilingual, multiple
pluri
ie. plural wife, pluralism
– poly-
ie. polyhedra, polygamy, polypod, polyglot, polymath
pollakis-
(many times)
pollaplo-
(multiple)
plethos, plethora
(many of a kind)
pollosto-
(rank/order of many [manieth])
bahu–

Sesqui- is used in Latin combinations for 1½ (e.g. sesquicentennial) and quasqui- for 1¼; multi- and poly- are used in Latin and Greek combinations, respectively, for 'many' (multilateral, polygon).

*For Latinate 21, 22, etc., the pattern for the teens is followed: unvigint-, duovigint-, etc. For higher numbers, the reverse order may be found: 36 trigintisex-. For Greek, the word kai ('and') is used: icosikaihena-, icosikaidi-, pentacontakaipenta-, etc. In these and in the tens, the kai is frequently omitted, though not in triskaidekaphobia. (The inconsistency of triskaidekaphobia with the table above is explained by the fact that the Greek letter kappa can be transliterated either "c" or "k".)

The same suffix may be used with more than one series:

 primary secondary tertiary quartary quintary sextary — — nonary — singulary binary ternary, trinary quaternary quinary senary septenary octonary novenary denary

In chemical nomenclature, 11 is generally mixed Latin-Greek undeca-, and the 20s are based on -cos-, for example tricos- for 23. Similarly, numerical bases shift systems between binary, trinary, senary and octal, decimal, vigesimal.

**The full numbering adjectives in Greek are inflectional for grammatical gender (ie. there is monos [masculine for single/alone], mone [feminine for single/alone] and monon [neuter for single/alone]), grammatical case (ie. nominative, genitive etc.) and grammatical number (singular/plural). The prefixes are produced from the default grammatical type (masculine/nominative/singular).

## Occurrences

• Numerical prefixes occur in 19th-, 20th-, and 21st-century coinages, mainly the terms that are used in relation to or that are the names of technological innovations, such as hexadecimal and bicycle. Also used in medals that commemorate an anniversary, such as sesquicentennial (150 years), centennial (100 years), or bicentennial (200 years).
• They occur in constructed words such as systematic names. Systematic names use numerical prefixes derived from Greek, with one principal exception, nona-.
• They occur as prefixes to units of measure in the SI system. See SI prefix.
• They occur as prefixes to units of computer data. See binary prefixes.
• They occur in words in the same languages as the original number word, and their respective derivatives. (Strictly speaking, some of the common citations of these occurrences are not in fact occurrences of the prefixes. For example: millennium is not formed from milli-, but is in fact derived from the same shared Latin root – mille.)

Because of the common inheritance of Greek and Latin roots across the Romance languages, the import of much of that derived vocabulary into non-Romance languages (such as into English via Norman French), and the borrowing of 19th and 20th century coinages into many languages, the same numerical prefixes occur in many languages.

Numerical prefixes are not restricted to denoting integers. Some of the SI prefixes denote negative powers of 10, i.e. division by a multiple of 10 rather than multiplication by it. Several common-use numerical prefixes denote vulgar fractions.

Words containing non-technical numerical prefixes are usually not hyphenated. This is not an absolute rule, however, and there are exceptions (for example: quarter-deck occurs in addition to quarterdeck). There are no exceptions for words comprising technical numerical prefixes, though. Systematic names and words comprising SI prefixes and binary prefixes are not hyphenated, by definition.

Nonetheless, for clarity, dictionaries list numerical prefixes in hyphenated form, to distinguish the prefixes from words with the same spellings (such as duo- and duo).

Several technical numerical prefixes are not derived from words for numbers. (mega- is not derived from a number word, for example.) Similarly, some are only derived from words for numbers inasmuch as they are word play. (Peta- is word play on penta-, for example. See its etymology for details.)

The root language of a numerical prefix need not be related to the root language of the word that it prefixes. Some words comprising numerical prefixes are hybrid words.

In certain classes of systematic names, there are a few other exceptions to the rule of using Greek-derived numerical prefixes. The IUPAC nomenclature of organic chemistry, for example, uses the numerical prefixes derived from Greek, except for the prefix for 9 (as mentioned) and the prefixes from 1 to 4 (meth-, eth-, prop-, and but-), which are not derived from words for numbers. These prefixes were invented by the IUPAC, deriving them from the pre-existing names for several compounds that it was intended to preserve in the new system: methane (via methyl which is in turn from the Greek word for wine), ethane (from ethyl coined by Justus von Liebig in 1834), propane (from propionic which is in turn from pro- and the Greek word for fat), and butane (from butyl which is in turn from butyric which is in turn from the Latin word for butter).

## Cardinal Latin series

• unicycle, bicycle, tricycle, quadricycle
• uniped, biped, triped, quadruped,[11] centipede, millipede

## Distributive Latin series

• unary, binary, trinary, quaternary, quinary, senary, … vicenary … centenary …
• quinquagenarian, sexagenarian, septuagenarian, octogenarian, nonagenarian, centenarian, … millenarian

## Notes

1. ^ a b See Mendeleev's predicted elements for the most common use of Sanskrit numerical prefixes.
2. ^ Demi- is French, from Latin dimidium.
3. ^ sim- (sin-) is found in the words simplex, simple.
4. ^ a b The Greek prefix for 'one' is normally mono- 'alone'. Hen- 'one' is only used in compound numbers (hendeka- 11) and a few words like henad (= monad). Haplo- 'single' is found is a few technical words such as haploid.
5. ^
6. ^ δύο
7. ^ δίς
8. ^ δεύτερος
9. ^ τρίς
10. ^ τρίτος
11. ^ a b The forms related to quattuor "four", like the previous three integers, are irregular in Latin and other Indo-European languages, and the details, while presumably a form of assimilation, are unclear. Andrew Sihler, New comparative grammar of Greek and Latin, p. 412, and Carl Darling Buck, Comparative grammar of Greek and Latin. In particular, quadri- has the alternate form quadru- before p in some Latin words, such as quadruple.
12. ^ "quăter". Retrieved 2011-05-14.
13. ^ "quăterni". Retrieved 2011-05-14.
14. ^ "quartus". Retrieved 2011-05-14.
15. ^ "quinque". Retrieved 2011-05-14.
16. ^ "quīni". Retrieved 2011-05-14.
17. ^ "quintus". Retrieved 2011-05-14.
18. ^ πέμπτος
19. ^ a b Sometimes Greek hexa- is used in Latin compounds, such as hexadecimal, due to taboo avoidance with the English word sex.
20. ^ "sēni". Retrieved 2011-05-14.
21. ^ "sextus". Retrieved 2011-05-14.
22. ^ ἕξ
23. ^ ἕκτος
24. ^ "septēni". Retrieved 2011-05-14.
25. ^ ἑπτά
26. ^ "octōni". Retrieved 2011-05-14.
27. ^ "octāvus". Retrieved 2011-05-14.
28. ^ ἐννέα
29. ^ ἔνατος
30. ^ "dēni". Retrieved 2011-05-14.
31. ^ "dĕcĭmus". Retrieved 2011-05-14.
32. ^ δέκα
33. ^ δέκατος
34. ^ "undēni". Retrieved 2011-05-14.
35. ^ "undĕcĭmus". Retrieved 2011-05-14.
36. ^ ἕνδεκα
37. ^ ἑνδέκατος
38. ^ δώδεκα
39. ^ δωδέκατος
40. ^ "quindĕcim". Retrieved 2011-05-14.
41. ^ "quindēni". Retrieved 2011-05-14.
42. ^ "quindĕcĭmus". Retrieved 2011-05-14.
43. ^ "sēdĕcim". Retrieved 2011-05-14.
44. ^ "quinquāginta". Retrieved 2011-05-14.
45. ^ "quinquāgēni". Retrieved 2011-05-14.
46. ^ "quinquāgēsĭmus". Retrieved 2011-05-14.
47. ^ "quingenti". Retrieved 2011-05-14.
48. ^ "quincenti". Retrieved 2011-05-14.
49. ^ "quingēni". Retrieved 2011-05-14.
50. ^ "quingentēsĭmus". Retrieved 2011-05-14.
51. ^ ἐννακόσιοι
52. ^ ἐνακοσιοστός
53. ^ χίλιοι
54. ^ χιλιοστός
55. ^ δισχίλιοι
56. ^ τρισχίλιοι
57. ^ τρισχιλιοστός
58. ^ πεντακισχίλιοι
59. ^ μυρίος
60. ^ μυριαστός
61. ^ ὀκτακισμύριοι
62. ^ In organic chemistry, the prefix for 9 is Latin rather than Greek