Prefix

A prefix is an affix which is placed before the 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. Particularly in the study of languages, a prefix is also called a preformative, because it alters the form of the words to which it is affixed.

Prefixes, like other affixes, can be either inflectional, creating a new form of the word with the same basic meaning and same lexical category (but playing a different role in the sentence), or derivational, creating a new word with a new semantic meaning and sometimes also a different lexical category. Prefixes, like all other affixes, are usually bound morphemes.

In English, there are no inflectional prefixes; English uses suffixes instead for that purpose.

The word prefix is itself made up of the stem fix (meaning "attach", in this case), and the prefix pre- (meaning "before"), both of which are derived from Latin roots.

In English, a fairly comprehensive list, although not exhaustive, is the following. Depending on precisely how one defines a derivational prefix, some of the neoclassical combining forms may or may not qualify for inclusion in such a list. This list takes the broad view that acro- and auto- count as English derivational prefixes because they function the same way that prefixes such as over- and self- do.

As for numeral prefixes, only the most common members of that class are included here. There is a large separate table covering them all at Numeral prefix > Table of number prefixes in English.

binomial, "two terms"

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