Numeral or number prefixes are

prefix A prefix is an affix which is placed before the Word stem, stem of a word. Adding it to the beginning of one word changes it into another word. For example, when the prefix ''un-'' is added to the word ''happy'', it creates the word ''unhappy'' ...

es derived from numerals or occasionally other

number A number is a mathematical object used to count, measure, and label. The original examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can be represented in language with number words. More universally, individual numbers c ...

s. In English and many other languages, they are used to coin numerous series of words. For example: * unicycle, bicycle, tricycle (1-cycle, 2-cycle, 3-cycle) * dyad, triad (2 parts, 3 parts) * biped, quadruped (2 legs, 4 legs) * September, October, November, December (month 7, month 8, month 9, month 10) * decimal, hexadecimal (base-10, base-16) * septuagenarian, octogenarian (70-79 years old, 80-89 years old) * centipede, millipede (around 100 legs, around 1000 legs) In many European languages there are two principal systems, taken from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

and Greek, each with several subsystems; in addition,

Sanskrit Sanskrit (; attributively , ; nominally , , ) is a classical language belonging to the Indo-Aryan branch of the Indo-European languages. It arose in South Asia after its predecessor languages had diffused there from the northwest in the late ...

occupies a marginal position. There is also an international set of

metric prefix A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or submultiple of the unit. All metric prefixes used today are decadic. Each prefix has a unique symbol that is prepended to any unit symbol. The pre ...

es, which are used in the

metric system The metric system is a system of measurement that succeeded the Decimal, decimalised system based on the metre that had been introduced in French Revolution, France in the 1790s. The historical development of these systems culminated in the d ...

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 number In mathematics, cardinal numbers, or cardinals for short, are a generalization of the natural numbers used to measure the cardinality (size) of sets. The cardinality of a finite set is a natural number: the number of elements in the set. Th ...

s, such as the English ''one, two, three.'' The ''multiple'' series are based on adverbial numbers like the English ''once, twice, thrice.'' The ''distributive'' series originally meant ''one each, two each'' or ''one by one, two by two,'' etc., though that meaning is now frequently lost. The ''ordinal'' series are based on

ordinal number In set theory, an ordinal number, or ordinal, is a generalization of ordinal numerals (first, second, th, etc.) aimed to extend enumeration to infinite sets. A finite set can be enumerated by successively labeling each element with the least n ...

s such as the English ''first, second, third'' (for numbers higher than 2, the ordinal forms are also used for fractions; only the fraction 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. The same suffix may be used with more than one series: : ; 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 In mathematics and computing, the hexadecimal (also base-16 or simply hex) numeral system is a positional numeral system that represents numbers using a radix (base) of 16. Unlike the decimal system representing numbers using 10 symbols, hexa ...

and

bicycle A bicycle, also called a pedal cycle, bike or cycle, is a human-powered or motor-powered assisted, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A is called a cyclist, or bicyclist. Bic ...

. Also used in medals that commemorate an

anniversary An anniversary is the date on which an event took place or an institution was founded in a previous year, and may also refer to the commemoration or celebration of that event. The word was first used for Catholic feasts to commemorate saints ...

, such as sesquicentennial (150 years),

centennial {{other uses, Centennial (disambiguation), Centenary (disambiguation) A centennial, or centenary in British English, is a 100th anniversary or otherwise relates to a century, a period of 100 years. Notable events Notable centennial events at a ...

(100 years), or

bicentennial __NOTOC__ A bicentennial or bicentenary is the two-hundredth anniversary of a part, or the celebrations thereof. It may refer to: Europe *French Revolution bicentennial, commemorating the 200th anniversary of 14 July 1789 uprising, celebrated ...

(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 The International System of Units, known by the international abbreviation SI in all languages and sometimes pleonastically as the SI system, is the modern form of the metric system and the world's most widely used system of measurement. E ...

. * 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 A millennium (plural millennia or millenniums) is a period of one thousand years, sometimes called a kiloannum (ka), or kiloyear (ky). Normally, the word is used specifically for periods of a thousand years that begin at the starting point (ini ...

is not formed from

milli- ''Milli'' (symbol m) is a unit prefix in the metric system denoting a factor of one thousandth (10−3). Proposed in 1793, and adopted in 1795, the prefix comes from the Latin , meaning ''one thousand'' (the Latin plural is ). Since 1960, the pre ...

, 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 language The Romance languages, sometimes referred to as Latin languages or Neo-Latin languages, are the various modern languages that evolved from Vulgar Latin. They are the only extant subgroup of the Italic languages in the Indo-European languages, I ...

s, the import of much of that derived vocabulary into non-Romance languages (such as into

English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ide ...

via

Norman French Norman or Norman French (, french: Normand, Guernésiais: , Jèrriais: ) is a Romance language which can be classified as one of the Oïl languages along with French, Picard and Walloon. The name "Norman French" is sometimes used to descri ...

), 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 The quarterdeck is a raised deck behind the main mast of a sailing ship. Traditionally it was where the captain commanded his vessel and where the ship's colours were kept. This led to its use as the main ceremonial and reception area on bo ...

occurs in addition to

quarterdeck The quarterdeck is a raised deck behind the main mast of a sailing ship. Traditionally it was where the captain commanded his vessel and where the ship's colours were kept. This led to its use as the main ceremonial and reception area on bo ...

). There are no exceptions for words comprising technical numerical prefixes, though. Systematic names and words comprising

es 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 Duo may refer to: Places *Duo, West Virginia, an unincorporated community and coal town in Greenbrier County, West Virginia *Duo, Tampere, a shopping centre in Hervanta, Tampere, Finland * DUO, a twin-tower development in Singapore Arts, enterta ...

). Several technical numerical prefixes are not derived from words for numbers. (

mega- Mega is a metric prefix, unit prefix in metric systems of units denoting a factor of one million (106 or 1000000 (number), ). It has the unit symbol M. It was confirmed for use in the International System of Units (SI) in 1960. ''Mega'' comes fro ...

is not derived from a number word, for example.) Similarly, some are only derived from words for numbers inasmuch as they are

word play Word play or wordplay (also: play-on-words) is a literary technique and a form of wit in which words used become the main subject of the work, primarily for the purpose of intended effect or amusement. Examples of word play include puns, phonet ...

. ( Peta- is word play on

penta- 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: * unicycle, bicycle, tricycle (1-cycle, 2-cycle, 3-cy ...

, 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 Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...

(via

methyl In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in many ...

, which is in turn from the Greek word for wine), ethane (from

ethyl Ethyl may refer to: Arts and entertainment * Cold Ethyl, a Swedish rock band *Ethyl Sinclair, a character in the ''Dinosaurs'' television show Science and technology * Ethyl group, an organic chemistry moiety * Ethyl alcohol (or ethanol) * E ...

coined by

Justus von Liebig Justus Freiherr von Liebig (12 May 1803 – 20 April 1873) was a German scientist who made major contributions to agricultural and biological chemistry, and is considered one of the principal founders of organic chemistry. As a professor at t ...

in 1834),

propane Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used a ...

(from propionic, which is in turn from

pro- This is a list of common affixes used when scientifically naming species, particularly extinct species for whom only their scientific names are used, along with their derivations. *a-, an-: ''Pronunciation'': /ə/, /a/, /ən/, /an/. ''Origin'' ...

and the Greek word for fat), and

butane Butane () or ''n''-butane is an alkane with the formula C4H10. Butane is a gas at room temperature and atmospheric pressure. Butane is a highly flammable, colorless, easily liquefied gas that quickly vaporizes at room temperature. The name but ...

(from butyl, which is in turn from butyric, which is in turn from the Latin word for butter).

Cardinal Latin series

unicycle A unicycle is a vehicle that touches the ground with only one wheel. The most common variation has a bicycle frame, frame with a bicycle saddle, saddle, and has a human-powered vehicle, pedal-driven direct-drive mechanism, direct-drive. A two spee ...

, tricycle, quadricycle *

uniped A uniped (from Latin ''uni-'' "one" and ''ped-'' "foot") is a person or creature with only one foot and one leg, as contrasted with a biped (two legs) and a quadruped (four legs). Moving using only one leg is known as unipedal movement. Many bival ...

, biped,

triped Tripedalism (from the Latin tri = three + ped = foot) is locomotion by the use of three limbs. It has been said that parrots ( Psittaciformes) display tripedalism during climbing gaits, which was tested and proven in a 2022 paper on the subject, m ...

, quadruped,

centipede Centipedes (from New Latin , "hundred", and Latin , " foot") are predatory arthropods belonging to the class Chilopoda (Ancient Greek , ''kheilos'', lip, and New Latin suffix , "foot", describing the forcipules) of the subphylum Myriapoda, an ...

, millipede

Distributive Latin series

*unary, binary, trinary, quaternary, quinary, senary, … vicenary … centenary … *denarian, vicenarian, tricenarian, quadragenarian, quinquagenarian, sexagenarian, septuagenarian, octogenarian, nonagenarian, centenarian, … millenarian

Greek series

* monad, dyad,

triad Triad or triade may refer to: * a group of three Businesses and organisations * Triad (American fraternities), certain historic groupings of seminal college fraternities in North America * Triad (organized crime), a Chinese transnational orga ...

, tetrad, pentad, hexad, heptad, ogdoad,

ennead The Ennead or Great Ennead was a group of nine deities in Egyptian mythology worshipped at Heliopolis: the sun god Atum; his children Shu and Tefnut; their children Geb and Nut; and their children Osiris, Isis, Set, and Nephthys. The Ennead ...

, decad, ... triacontad, ... hecatontad, chiliad,

myriad A myriad (from Ancient Greek grc, μυριάς, translit=myrias, label=none) is technically the number 10,000 (ten thousand); in that sense, the term is used in English almost exclusively for literal translations from Greek, Latin or Sinospher ...

* digon, trigon,

tetragon In Euclidean geometry, geometry a quadrilateral is a four-sided polygon, having four Edge (geometry), edges (sides) and four Vertex (geometry), corners (vertices). The word is derived from the Latin words ''quadri'', a variant of four, and ''l ...

pentagon In geometry, a pentagon (from the Greek πέντε ''pente'' meaning ''five'' and γωνία ''gonia'' meaning ''angle'') is any five-sided polygon or 5-gon. The sum of the internal angles in a simple pentagon is 540°. A pentagon may be simpl ...

hexagon In geometry, a hexagon (from Ancient Greek, Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple polygon, simple (non-self-intersecting) hexagon is 720°. Regular hexa ...

, heptagon,

octagon In geometry, an octagon (from the Greek ὀκτάγωνον ''oktágōnon'', "eight angles") is an eight-sided polygon or 8-gon. A '' regular octagon'' has Schläfli symbol and can also be constructed as a quasiregular truncated square, t, whi ...

enneagon In geometry, a nonagon () or enneagon () is a nine-sided polygon or 9-gon. The name ''nonagon'' is a prefix hybrid formation, from Latin (''nonus'', "ninth" + ''gonon''), used equivalently, attested already in the 16th century in French ''nonogo ...

, decagon, hendecagon,

dodecagon In geometry, a dodecagon or 12-gon is any twelve-sided polygon. Regular dodecagon A regular dodecagon is a figure with sides of the same length and internal angles of the same size. It has twelve lines of reflective symmetry and rotational sym ...

, ... enneadecagon,

icosagon In geometry, an icosagon or 20-gon is a twenty-sided polygon. The sum of any icosagon's interior angles is 3240 degrees. Regular icosagon The regular icosagon has Schläfli symbol , and can also be constructed as a truncated decagon, , or a t ...

triacontagon In geometry, a triacontagon or 30-gon is a thirty-sided polygon. The sum of any triacontagon's interior angles is 5040 degrees. Regular triacontagon The '' regular triacontagon'' is a constructible polygon, by an edge- bisection of a regular ...

, ... chiliagon,

myriagon In geometry, a myriagon or 10000-gon is a polygon with 10,000 sides. Several philosophers have used the regular myriagon to illustrate issues regarding thought. Meditation VI by Descartes (English translation). Regular myriagon A regular myriag ...

trilogy A trilogy is a set of three works of art that are connected and can be seen either as a single work or as three individual works. They are commonly found in literature, film, and video games, and are less common in other art forms. Three-part wor ...

tetralogy A tetralogy (from Greek τετρα- ''tetra-'', "four" and -λογία ''-logia'', "discourse") is a compound work that is made up of four distinct works. The name comes from the Attic theater, in which a tetralogy was a group of three tragedies ...

pentalogy A pentalogy (from Greek πεντα- ''penta-'', "five" and -λογία ''-logia'', "discourse") is a compound literary or narrative work that is explicitly divided into five parts. Although modern use of the word implies both that the parts are re ...

hexalogy A hexalogy (from Greek ἑξα- '' hexa-'', "six" and -λογία ''-logia'', "discourse") is a compound literary or narrative work that is made up of six distinct works. The word apparently first appeared in English as a borrowing from German, in ...

heptalogy A heptalogy (; from Greek ἑπτα- ''hepta-'', "seven" and -λογία ''-logia'', "discourse"), also known as a septology, is a compound literary or narrative work that is made up of seven distinct works. While not in wide usage, it has been u ...

* monopod,

dipod A bipod is a V-shaped portable attachment that helps support and steady a device, usually a weapon such as a long gun or a mortar. The term comes from the Latin prefix ''bi-'' and Greek root ''pod'', meaning "two" and "foot" respectively. Bipod ...

, tripod,

tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids (pelycosaurs, extinct theraps ...

, hexapod,

octopod An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish ...

, decapod

Mixed language series

pentane Pentane is an organic compound with the formula C5H12—that is, an alkane with five carbon atoms. The term may refer to any of three structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, pentane means exclusively the ' ...

hexane Hexane () is an organic compound, a straight-chain alkane with six carbon atoms and has the molecular formula C6H14. It is a colorless liquid, odorless when pure, and with boiling points approximately . It is widely used as a cheap, relatively ...

, heptane,

octane Octane is a hydrocarbon and an alkane with the chemical formula , and the condensed structural formula . Octane has many structural isomers that differ by the amount and location of branching in the carbon chain. One of these isomers, 2,2,4-Tri ...

nonane Nonane is a linear alkane hydrocarbon with the chemical formula C9H20. It is a colorless, flammable liquid, occurring primarily in the component of the petroleum distillate fraction commonly called kerosene, which is used as a heating, tractor, ...

, decane,

undecane Undecane (also known as hendecane) is a liquid alkane hydrocarbon with the chemical formula CH3(CH2)9CH3. It is used as a mild sex attractant for various types of moths and cockroaches, and an alert signal for a variety of ants.Hölldobler B, Wils ...

, ...

icosane Icosane (alternative spelling eicosane) is an alkane with the chemical formula C20H42. It has 366,319 constitutional isomers. Icosane has little use in the petrochemical industry, as its high flash point makes it an inefficient fuel. ''n''-Icosane ...

binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that t ...

ternary Ternary (from Latin ''ternarius'') or trinary is an adjective meaning "composed of three items". It can refer to: Mathematics and logic * Ternary numeral system, a base-3 counting system ** Balanced ternary, a positional numeral system, useful ...

quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...

quinary Quinary (base-5 or pental) is a numeral system with five as the base. A possible origination of a quinary system is that there are five digits on either hand. In the quinary place system, five numerals, from 0 to 4, are used to represent an ...

senary A senary () numeral system (also known as base-6, heximal, or seximal) has six as its base. It has been adopted independently by a small number of cultures. Like decimal, it is a semiprime, though it is unique as the product of the only two con ...

septenary There are many different numeral systems, that is, writing systems for expressing numbers. By culture / time period By type of notation Numeral systems are classified here as to whether they use positional notation (also known as place-value ...

octal The octal numeral system, or oct for short, is the radix, base-8 number system, and uses the Numerical digit, digits 0 to 7. This is to say that 10octal represents eight and 100octal represents sixty-four. However, English, like most languages, ...

nonary A ternary numeral system (also called base 3 or trinary) has 3 (number), three as its radix, base. Analogous to a bit, a ternary numerical digit, digit is a trit (trinary digit). One trit is equivalent to binary logarithm, log2 3 (about 1.5 ...

decimal The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers of the Hindu–Arabic numeral ...

duodecimal The duodecimal system (also known as base 12, dozenal, or, rarely, uncial) is a positional notation numeral system using twelve as its base. The number twelve (that is, the number written as "12" in the decimal numerical system) is instead wri ...

vigesimal vigesimal () or base-20 (base-score) numeral system is based on twenty (in the same way in which the decimal numeral system is based on ten). '' Vigesimal'' is derived from the Latin adjective '' vicesimus'', meaning 'twentieth'. Places In ...

quadrovigesimal Positional notation (or place-value notation, or positional numeral system) usually denotes the extension to any base of the Hindu–Arabic numeral system (or decimal system). More generally, a positional system is a numeral system in which the ...

duotrigesimal Base32 is the base-32 numeral system. It uses a set of 32 digits, each of which can be represented by 5 bits (25). One way to represent Base32 numbers in a human-readable way is by using a standard 32-character set, such as the twenty-two upper- ...

sexagesimal Sexagesimal, also known as base 60 or sexagenary, is a numeral system with sixty as its base. It originated with the ancient Sumerians in the 3rd millennium BC, was passed down to the ancient Babylonians, and is still used—in a modified form� ...

octogesimal There are many different numeral systems, that is, writing systems for expressing numbers. By culture / time period By type of notation Numeral systems are classified here as to whether they use positional notation (also known as place-value ...

Notes

References

Bibliography

* * * * * {{refend Prefixes Numeral systems