inflection

Inflection is a linguistic process by which a word changes form to encode grammatical information. Inflected forms reflect features such as tense, aspect, mood, voice, person, number, gender, case, and definiteness. Inflection can be realized through affixation (adding prefixes, suffixes, or infixes), through internal vowel or consonant changes (ablaut, umlaut), or through suppletion, where an entirely different word form is used.

Inflection contrasts with derivation, which creates new words or changes word class rather than merely modifying grammatical meaning. An inflected word typically remains the same lexeme, with its form varying according to context. English uses inflection for verbs and nouns, as in walk versus walks or walked, and dog versus dogs; adjectives can take comparative and superlative forms such as big, bigger, biggest.

Languages differ in the amount and type of inflection they employ. Some are fusional, packing several grammatical meanings into a single affix; others are agglutinative, attaching multiple discrete affixes with clear boundaries; yet others are analytic or isolating, relying on separate words with little inflection. Inflection often marks nouns and adjectives for case and agreement, and verbs for subject concord and tense, aspect, or mood. It helps indicate syntactic relations and can interact with word order, styles, and discourse structure.

Inflectional systems vary historically, with regular patterns shaped by sound changes and language contact, as well as irregular forms that resist regularization. The study of inflection includes analyzing paradigms, stem alternations, and the conditions under which a language deploys specific inflections.