Numeral or number prefixes are

prefix A prefix is an affix which is placed before the stem of a word. Particularly in the study of languages, a prefix is also called a preformative, because it alters the form of the word to which it is affixed. Prefixes, like other affixes, can b ...

es derived from numerals or occasionally other

number A number is a mathematical object used to count, measure, and label. The most basic 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 can ...

s. In English and many other languages, they are used to coin numerous series of words. For example: *

triangle A triangle is a polygon with three corners and three sides, one of the basic shapes in geometry. The corners, also called ''vertices'', are zero-dimensional points while the sides connecting them, also called ''edges'', are one-dimension ...

quadrilateral 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 () is any five-sided polygon or 5-gon. The sum of the internal angles in a simple polygon, simple pentagon is 540°. A pentagon may be simple or list of self-intersecting polygons, self-intersecting. A self-intersecting ...

, hexagon,

octagon In geometry, an octagon () 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, which alternates two types of edges. A truncated octagon, t is a ...

(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 A unicycle is a vehicle that touches the ground with only one wheel. The most common variation has a frame with a saddle, and has a pedal-driven direct-drive. A two speed hub is commercially available for faster unicycling. Unicycling is prac ...

bicycle A bicycle, also called a pedal cycle, bike, push-bike or cycle, is a human-powered transport, human-powered or motorized bicycle, motor-assisted, bicycle pedal, pedal-driven, single-track vehicle, with two bicycle wheel, wheels attached to a ...

tricycle A tricycle, sometimes abbreviated to trike, is a Human-powered transport, human-powered (or gasoline or electric motor powered or assisted, or gravity powered) Three-wheeler, three-wheeled vehicle. Some tricycles, such as cycle rickshaws (for pa ...

(vehicle with 1 wheel, 2 wheels, 3 wheels) * dyad, triad, tetrad (2 parts, 3 parts, 4 parts) * twins,

triplets A multiple birth is the culmination of a multiple pregnancy, wherein the mother gives birth to two or more babies. A term most applicable to vertebrate species, multiple births occur in most kinds of mammals, with varying frequencies. Such births ...

, quadruplets (multiple birth of 2 children, 3 children, 4 children) * biped,

quadruped Quadrupedalism is a form of locomotion in which animals have four legs that are used to bear weight and move around. An animal or machine that usually maintains a four-legged posture and moves using all four legs is said to be a quadruped (fr ...

, hexapod (animal with 2 feet, 4 feet, 6 feet) * September, October, November, December ( 7th month, 8th month, 9th month, 10th month) * binary, ternary,

octal Octal (base 8) is a numeral system with eight as the base. In the decimal system, each place is a power of ten. For example: : \mathbf_ = \mathbf \times 10^1 + \mathbf \times 10^0 In the octal system, each place is a power of eight. For ex ...

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 (''decimal fractions'') of th ...

hexadecimal Hexadecimal (also known as base-16 or simply hex) is a Numeral system#Positional systems in detail, positional numeral system that represents numbers using a radix (base) of sixteen. Unlike the decimal system representing numbers using ten symbo ...

(numbers expressed in base 2, base 3, base 8, base 10, base 16) * septuagenarian, octogenarian (a person 70–79 years old, 80–89 years old) *

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

millipede Millipedes (originating from the Latin , "thousand", and , "foot") are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derive ...

, myriapod (subgroups of

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

s with numerous feet, suggesting but not implying approximately 100, , and feet respectively) In many European languages there are two principal systems, taken from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

and Greek, each with several subsystems; in addition,

Sanskrit Sanskrit (; stem form ; nominal singular , ,) is a classical language belonging to the Indo-Aryan languages, Indo-Aryan branch of the Indo-European languages. It arose in northwest South Asia after its predecessor languages had Trans-cultural ...

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 pr ...

es, 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 number In mathematics, a cardinal number, or cardinal for short, is what is commonly called the number of elements of a set. In the case of a finite set, its cardinal number, or cardinality is therefore a natural number. For dealing with the cas ...

s, such as the English ''one'', ''two'', ''three'', which name the count of items in a sequence. The ''multiple'' category are

adverb An adverb is a word or an expression that generally modifies a verb, an adjective, another adverb, a determiner, a clause, a preposition, or a sentence. Adverbs typically express manner, place, time, frequency, degree, or level of certainty by ...

ial 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 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 leas ...

s 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 orginary 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 Scientific notation is a way of expressing numbers that are too large or too small to be conveniently written in decimal form, since to do so would require writing out an inconveniently long string of digits. It may be referred to as scientif ...

SI prefix The International System of Units, internationally known by the abbreviation SI (from French ), is the modern form of the metric system and the world's most widely used system of measurement. It is the only system of measurement with official st ...

es are used to express very large or very small numbers, and not unwieldy prefixes. ; 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

and

. Also used in medals that commemorate an

anniversary An anniversary is the date on which an event took place or an institution was founded. Most countries celebrate national anniversaries, typically called national days. These could be the List of national independence days, date of independen ...

, such as sesquicentennial (150 years), centennial (100 years), or bicentennial (200 years). * They occur in constructed words such as

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivi ...

s. 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

. * They occur as prefixes to units of computer data. See

binary prefixes A binary prefix is a unit prefix that indicates a multiple of a unit of measurement by an integer power of two. The most commonly used binary prefixes are kibi (symbol Ki, meaning ), mebi (), and gibi (). They are most often used in inform ...

. * 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 () is a period of one thousand years, one hundred decades, or ten centuries, 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 ...

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 language The Romance languages, also known as the Latin or Neo-Latin languages, are the languages that are Language family, directly descended from Vulgar Latin. They are the only extant subgroup of the Italic languages, Italic branch of the Indo-E ...

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

Norman French Norman or Norman French (, , Guernésiais: , Jèrriais: ) is a '' langue d'oïl'' spoken in the historical and cultural region of Normandy. The name "Norman French" is sometimes also used to describe the administrative languages of '' Angl ...

), 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 name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivi ...

s 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). 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, ph ...

. ( Peta- is word play on penta-, for example. See its etymology for details.) The

es peta, exa, zetta, yotta, ronna, and quetta are based on the Ancient Greek or Ancient Latin numbers from 5 to 10, referring to the fifth through tenth powers of . The initial letter h has been removed from some of these stems and the initial letters z, y, r, and q have been added, ascending in reverse alphabetical order, to avoid confusion with other metric prefixes. 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 word A hybrid word or hybridism is a word that etymologically derives from at least two languages. Such words are a type of macaronic language. Common hybrids The most common form of hybrid word in English combines Latin and Greek parts. Since m ...

s. 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 In chemical nomenclature, the IUPAC nomenclature of organic chemistry is a method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC). It is published in the '' Nomenclature of O ...

, 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 abundance of methane on Earth makes ...

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

ethane Ethane ( , ) is a naturally occurring Organic compound, organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is List of purification methods ...

(from ethyl coined by Justus von Liebig in 1834),

propane Propane () is a three-carbon chain alkane with the molecular formula . It is a gas at standard temperature and pressure, but becomes liquid when compressed for transportation and storage. A by-product of natural gas processing and petroleum ref ...

(from propionic, which is in turn from pro- and the Greek word for fat), and

butane Butane () is an alkane with the formula C4H10. Butane exists as two isomers, ''n''-butane with connectivity and iso-butane with the formula . Both isomers are highly flammable, colorless, easily liquefied gases that quickly vaporize at ro ...

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

Cardinal Latin series

, quadricycle * uniped, biped, triped,

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, tetrad, pentad, hexad, heptad, ogdoad, ennead, decad, ... triacontad, ... hecatontad, chiliad, myriad * digon, trigon, tetragon,

, hexagon, heptagon,

, enneagon, decagon, hendecagon,

dodecagon In geometry, a dodecagon, or 12-gon, is any twelve-sided polygon. Regular dodecagon A regular polygon, 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 ...

, ... 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 polygon, regular icosagon has Schläfli symbol , and can also be constructed as a Truncation ( ...

, triacontagon, ... chiliagon, myriagon *

trilogy A trilogy is a set of three distinct works 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. Three-part works that are considered components of ...

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, hexalogy,

heptalogy Series fiction refers to a group of independently published works of fiction that are related to one another, usually through similar elements of setting and Fictional character, characters. A common example of series fiction is a book series. Seri ...

* monopod, dipod,

tripod A tripod is a portable three-legged frame or stand, used as a platform for supporting the weight and maintaining the stability of some other object. The three-legged (triangular stance) design provides good stability against gravitational loads ...

tetrapod A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetr ...

, hexapod, octopod, decapod

Mixed language series

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

hexane Hexane () or ''n''-hexane is an organic compound, a straight-chain alkane with six carbon atoms and the molecular formula C6H14. Hexane is a colorless liquid, odorless when pure, and with a boiling point of approximately . It is widely used as ...

, heptane,

octane Octane is a hydrocarbon and also an alkane with the chemical formula C8H18, and the condensed structural formula CH3(CH2)6CH3. Octane has many structural isomers that differ by the location of branching in the carbon chain. One of these isomers ...

, nonane, 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. It has 159 isomer ...

, ... icosane * binary, ternary,

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), as well as the current and most recent of the twelve periods of the ...

, quinary,

senary A senary () numeral system (also known as base-6, heximal, or seximal) has 6, six as its radix, base. It has been adopted independently by a small number of cultures. Like the decimal base 10, the base is a semiprime, though it is unique as the p ...

septenary There are many different numeral systems, that is, writing systems for expressing numbers. By culture / time period "A ''base'' is a natural number B whose ''powers'' (B multiplied by itself some number of times) are specially designated w ...

, nonary,

duodecimal The duodecimal system, also known as base twelve or dozenal, is a positional numeral system using twelve as its base. In duodecimal, the number twelve is denoted "10", meaning 1 twelve and 0 units; in the decimal system, this number is i ...

vigesimal A vigesimal ( ) or base-20 (base-score) numeral system is based on 20 (number), twenty (in the same way in which the decimal, decimal numeral system is based on 10 (number), ten). ''wikt:vigesimal#English, Vigesimal'' is derived from the Latin a ...

, quadrovigesimal, duotrigesimal,

sexagesimal Sexagesimal, also known as base 60, is a numeral system with 60 (number), sixty as its radix, 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 fo ...

Table of number prefixes in English

Occurrences

Cardinal Latin series

Distributive Latin series

Greek series

Mixed language series

See also

Notes

References

Bibliography