Numeral Prefix - Occurrences

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 comprising 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).