suppletieve

Suppletieve, or suppletive, is a term used in linguistics to describe a form in a language that cannot be predicted by a regular pattern of inflection because it is drawn from a different etymological root than the rest of the word’s paradigm. The term derives from Latin suppletio, meaning “to supply” or “to fill up,” and it is used to explain irregularities in inflection that are not the result of simple sound changes or productive analogy.

A classic example occurs in English verb morphology. The forms of the verb to be—am, is, are, was, were, been—derive from different historical roots within the same verb family, so they do not form a single, phonologically regular pattern. The past tense of go is went, a form that comes from a different verb stem (wend-) and therefore appears suppletive relative to go. Adjectival comparison often cited as suppletive is good, better, best, where the comparative and superlative come from a different historical root than good, illustrating how suppletion can affect comparative morphology.

Suppletion is found in many languages, especially those with rich inflection or strong historical layering. It commonly involves verb paradigms (such as be-like verbs), adjectives, or other word classes where forms diverge from a single productive rule and instead rely on entirely different roots for different grammatical contexts (tense, number, degree, etc.). It is distinguished from ordinary irregularity caused by phonological change or analogy because suppletive forms cannot be derived by a uniform, intra-lexical rule from the base form.

In linguistic analysis, recognizing suppletion helps explain seemingly irregular patterns and clarifies how historically unrelated forms can come to serve the same grammatical function within a paradigm.