Prefixes

Prefixes are affixes attached to the beginning of a word or stem to modify its meaning or grammatical function. They are bound morphemes, meaning they cannot stand alone, and are a primary tool for word formation in many languages.

In linguistic morphology, prefixes are often divided into derivational prefixes, which create new words or change a word’s lexical category (for example un- in unhappy, re- in rewrite, pre- in prehistoric). Inflectional prefixes exist in some languages but are less common in English; more broadly, prefixes in different languages can mark negation, direction, aspect, or other grammatical features.

Common English prefixes include un-, re-, pre-, dis-, mis-, in-/im-/il-/ir-, de-, inter-, sub-, and super-. They can convey negation (unhappy), repetition or return (retry), time or position (prehistory), reversal (disappear, deactivate), or order and scope (intercontinental, submarine). Prefixes may produce spelling and pronunciation changes; for example, in- becomes im- before p, b, or m (impossible, impossible), and in- as a negative before certain roots leads to impossible forms. Productivity varies: highly productive prefixes can generate new words, while others are more limited or stylistically constrained.

In science and mathematics, prefixes also denote scale or order of magnitude, such as kilo-, centi-, milli-, and micro-, used with units of measure.

See also: affix, morpheme, derivation, inflection, etymology.