Numeral or number prefixes are prefixes derived from numerals or occasionally other numbers. In English and many other languages, they are used to coin numerous series of words. For example:
triangle, quadrilateral, pentagon, hexagon, octagon (shape with 3 sides, 4 sides, 5 sides, 6 sides, 8 sides) simplex, duplex (communication in only 1 direction at a time, in 2 directions simultaneously) unicycle, bicycle, tricycle (vehicle with 1 wheel, 2 wheels, 3 wheels) dyad, triad, tetrad (2 parts, 3 parts, 4 parts) twins, triplets, quadruplets (multiple birth of 2 children, 3 children, 4 children) biped, quadruped, hexapod (animal with 2 feet, 4 feet, 6 feet) September, October, November, December (7th month, 8th month, 9th month, 10th month) binary, ternary, octal, decimal, hexadecimal (numbers expressed in base 2, base 3, base 8, base 10, base 16) Unary, binary, ternary, quaternary, quinary, senary, septenary, octonary, nonary, denary (related to having a certain number of something—parts, components, elements, divisions, etc.) septuagenarian, octogenarian (a person 70–79 years old, 80–89 years old) centipede, millipede, myriapod (subgroups of arthropods with numerous feet, suggesting but not implying approximately 100, , and feet respectively)
In many European languages there are two principal systems, taken from Latin and Greek, each with several subsystems; in addition, Sanskrit occupies a marginal position. There is also an international set of metric prefixes, which are used in the world's standard measurement system.
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 extended to bis- before a vowel; among the other monosyllables, du-, di-, dvi-, and tri-, never vary.
Words in the cardinal category are cardinal numbers, such as the English one, two, three, which name the count of items in a sequence. The multiple category are adverbial numbers, like the English once, twice, thrice, that specify the number of events or instances of otherwise identical or similar items. Enumeration with the distributive category originally was meant to specify one each, two each or one by one, two by two, etc., giving how many items of each type are desired or had been found, although distinct word forms for that meaning are now mostly lost. The ordinal category are based on ordinal numbers such as the English first, second, third, which specify position of items in a sequence. In Latin and Greek, the ordinal forms are also used for fractions for amounts higher than 2; only the fraction has special forms.
The same suffix may be used with more than one category of number, as for example the ordinal numbers secondary and tertiary and the distributive numbers binary and ternary.
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 through 9 .
Many of the items in the following tables are not in general use, but may rather be regarded as coinages by individuals. In scientific contexts, either scientific notation or SI prefixes are used to express very large or very small numbers, and not unwieldy prefixes.
+ Number prefixes in English Number Latinderived Greekderived Sanskrit Cardinal Multiple Distributive Ordinal Cardinal Multiple, proportional, orquantitative Ordinal 0 nulli- nullesim- miden-, ouden- medeproto-, oudeproto- shūnya- unci- Greek uses ordinals to name fractions; (i.e. dodecato-) octant- As above; ogdoö– sextant- As above; hecto quintant- As above; pempto– quadrant- As above; tetarto– trient- As above; trito– semi- demi- hemi- ("half") dodrant- colspan=3 1 uni-sol- sim- singul- prim- mono- ("one, alone")hapax- ("once")haplo- ("single")monad- ("one of a kind", "unique", "unit") prot-protaio- ("[every] first day") eka- quasqui- sesqui- 2 du- bi-, bis- bin- second- di-, dy-, duo-, dyo- dis- ("twice") commondyakis- ("twice") rarediplo- ("double")dyad- ("two of akind") deuter-deuteraio- ("[every] second day") dvi- sester-semiquin- 3 tri- ter- tern-, trin- terti- tri- tris- ("thrice") commontriakis- ("thrice") raretriplo- ("triple")triad- ("three of a kind") trit- ("third")tritaio- ("[every] third day") tri- 4 quadri-, quadru- quater- quatern- quart- tetra-, tessara- tetrakis- ("four times")tetraplo- ("quadruple")tetrad- ("four of a kind") tetarto- ("fourth")tetartaio-("[every] fourth day") catur- 5 quinque- quin- quint- penta- pentakis-pentaplo-pentad- pempt-pemptaio- pañca- 6 sexa- sen- sext- hexa- hexakis-hexaplo-hexad- hect-hectaio- ṣaṭ- 7 septem-, septi- septen- septim- hepta- heptakis-heptaplo-heptad- hebdomo- ("seventh")hebdomaio- ("seventh day") sapta- 8 octo- octon- octav- octo- octakis-octaplo-octad- ogdoö-ogdoaio- aṣṭa- 9 novem- noven- nona- ennea- enneakis-enneaplo-ennead- enat-enataio- nava- 10 decem-, dec- den- decim- deca- decakis- decaplo- decad- decat-decataio- dasha- 11 undec- unden- undecim- hendeca- hendeca/kis/plo/d- hendecat-/o/aio- ekadasha- 12 duodec- duoden- duodecim- dodeca- dodeca/kis/plo/d- dodecat-/o/aio- dvadasha- 13 tredec- treden- tredecim- tria(kai)deca-, decatria- tris(kai)decakis-,decatria/kis/plo/d- decatotrito- etc. trayodasha- 14 quattuordec- quattuorden- quattuordecim-quartadecim- tessara(kai)deca-, decatettara-, decatessara- tetra(kai)decakis-,decatetra/kis/plo/d- decatotetarto- chaturdasha- 15 quinquadec-, quindec- quinden- quindecim-quintadecim- pente(kai)deca-, decapente- penta(kai)decakis-,decapentakis- etc. decatopempto- panchadasha- 16 sedec-, sexdec- (but hybrid hexadecimal) seden- sedecim-sextadecim- hexa(kai)deca-,hekkaideca-,decahex- hexa(kai)decakis-, decahexakis- etc. decatohecto- shodasha- 17 septendec- septenden- septendecim-septimadecim- hepta(kai)deca-,decahepta- hepta(kai)decakis-,decaheptakis- etc. decatohebdomo- saptadasha- 18 octodec- octoden- octodecim-duodevicesim- octo(kai)deca-,decaocto- octa(kai)decakis-,decaoctakis- etc. decatoogdoö- ashtadasha- 19 novemdec-, novendec-undeviginti- novemden-novenden- novemdecim-novendecim-undevisim- ennea(kai)deca-, decaennea- ennea(kai)decakis-,decaenneakis- etc. decatoenato- navadasha- 20 viginti- vicen-, vigen- vigesim- (e)icosi- eicosa/kis/plo/d- eicosto- vimshati- 22 duovigint- (e)icosidyo-, dyo(e)icosi- rare (e)icosidyakis- (e)icosidiplo- (e)icosidyad- eicostodeutero- 24 quattuorvigint- (e)icositettara-, (e)icosikaitettara-rare (e)icositetrakis- (e)icositetraplo- (e)icositetrad- eicostotetarto- chaturvimshati- 25 quinvigint- (e)icosipente- (e)icosipentakis- (e)icosipentaplo- (e)icosipentad- eicostopempto- 30 triginti- tricen- trigesim- triaconta- triacontakis- etc. triacosto- trimshat- 31 untriginti- triacontahen- triacontahenakis- triacontahenaplo-triacontahenad- triacostoproto- triacostoprotaio- 40 quadraginti- quadragen- quadragesim- tettaraconta-,tessaraconta- tettaracontakis-,tessaracontakis- etc. tessaracosto- chatvarimshat- 50 quinquaginti- quinquagen- quinquagesim- penteconta- pentecontakis- etc. pentecosto- panchashat- 60 sexaginti- sexagen- sexagesim- hexeconta- hexecontakis- etc. hexecosto- shasti- 70 septuaginti- septuagen- septuagesim- 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 timeshecatontaplo-hundred-multiplehecatontad-hundred of a kindalso abbreviated inhec[aton]tad- hecatosto-hundredthhecatostaio-the hundredth day shata– 120 viginticenti- hecaton(e)icosi- hecaton(e)icosakis- etc. hecatostoeicosto- 150colspan=2 sesquicenten- 200 ducenti- ducen-, bicenten- ducentesim- diacosia- diacosakis- etc. diacosiosto- 250colspan=2 semiquincenten- 300 trecenti- trecen-, tercenten-, tricenten- trecentesim- triacosia- etc. triacosakis- triacosaplo- triacosad- triacosiosto- 400 quadringenti- quadringen-, quatercenten-, quadricenten- quadringentesim- tetracosia- tetracosakis- etc. tetracosiosto- 500 quingent-, quincent- quingen-, quingenten-, quincenten- quingentesim- 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-derived fromen(n)iacosia-,a pejoration ofenneacosia- enneacosakis- etc. enacosiost-,alt. spellingen(n)iacosiost(o)- a pejoration ofenneacosiosto- milli- millen- millesim- khili-, kilo- khiliakis- khiliaplo- chiliad- chiliost- sahasra– duomilli diskhili- diskhiliakis- etc. diskhiliosto- tremilli- triskhili- triskhiliost- quinmilli– pentaciskhili- decamilli– myria-, decakiskhilia- myriakis- myriaplo- myriad-decakiskhiliakis- etc. myriast-, decakiskhiliosto- ayuta– octogintmilli– octacismyri- or centimilli– decakismyria-, hecatontakiskhilia- decakismyriakis-,hecatontakiskhiliakis- etc. laksha– or colspan=4 hecatommyria- (see also mega-) hecatommyriakis- ("a million times") hecatommyriaplo-(million-multiple)hecatommyriad-(a million of a kind) hecatommyriosto-(ranked millionth;also one piece of a million [fraction] see above in fractions)hecatommyriostaio-("the millionth day") infini- apeiro- Few pauci- oligo- Many(more than 1) multi-, pluri- poly- pollakis- (many times)pollaplo- (multiple)plethos- (many of a kind) pollosto- (rank/order of many [manieth]) bahut–
Examples
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).