Numeral Prefix - Table of Number Prefixes in English

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 English one, two, three. The multiple series are based on adverbial numbers like 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 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.

Sesqui- is used in Latin combinations for 1½ (sesquicentennial) and quasqui- for 1¼; multi- and poly- are used in Latin and Greek combinations 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 undec-, 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.