suppletiv

Suppletive, or suppletive form, is a term in linguistics used to describe an inflected form that cannot be derived from the same lexical stem through regular affixation. In a suppletive paradigm, some forms are supplied by a different root or stem, rather than formed by predictable internal changes of a single stem. Suppletion is most noticeable in verbal inflection but can also occur with adjectives, pronouns, and numerals in various languages.

Classic examples are English verbs. The present tense forms of the verb to be—am, are, is—are not built from a single be-stem in a regular way, and the past tense was/were and the past participle been come from different roots or historically divergent paths. The verb go has present go, past went, and past participle gone, with went arising from a distinct root. Some analysts also treat good, better, best as a partially suppletive adjective pair, since the comparative and superlative forms do not arise by simple suffixation on the single adjective good.

Suppletive forms are described as complete when an entire paradigm uses different stems, and partial when only some forms are supplied from distinct roots. Suppletion is common in historic and comparative linguistics and often reflects older stages of a language, analogy, sound change, or language contact. It poses particular challenges for morphological theory and lexicon organization, because irregular forms must be stored and retrieved as separate root candidates rather than predictable inflection patterns.