English prefixes

English prefixes are affixes (i.e., bound morphemes that provide lexical meaning) that are added before either simple roots or complex bases (or operands) consisting of (a) a root and other affixes, (b) multiple roots, or (c) multiple roots and other affixes. Examples of these follow:

English words may consist of multiple prefixes: anti-pseudo-classicism (containing both an anti- prefix and a pseudo- prefix).

In English, all prefixes are derivational. This contrasts with English suffixes, which may be either derivational or inflectional.

As is often the case with derivational morphology, many English prefixes can only be added to bases of particular lexical categories (or "parts of speech"). For example, the prefix re- meaning "again, back" is only added to verb bases as in rebuild, reclaim, reuse, resell, re-evaluate, resettle. It cannot be added to bases of other lexical categories. Thus, examples of re- plus a noun base (such as the ungrammatical *rehusband, *remonopoly) or re- plus an adjective base (*renatural, *rewise) are virtually unattested.

These selectional restrictions on what base a prefix can be attached to can be used to distinguish between otherwise identical-sounding prefixes. For instance, there are two different un- prefixes in English: one meaning "not, opposite of", the other meaning "reverse action, deprive of, release from". The first prefix un- "not" is attached to adjective and participle bases while the second prefix un- "reverse action" is attached to either verb or noun bases. Thus, English can have two words that are pronounced and spelled the same and have the same lexical category but have different meanings, different prefixes, a different internal morphological structure, and different internal bases that the prefixes are attached to:

In the first unlockable "not able to be locked", the prefix un- "not" is attached to an adjective base lockable (which, in turn, is composed of lock + -able). This word has the following internal structure:

In the second unlockable "able to be unlocked", the prefix un- "reverse action" is attached to a verb base lock, resulting in the derived verb unlock. Subsequently, the -able suffix is added after the newly created unlock adjective base deriving the adjective unlockable. This word has the following internal structure:

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