suppletion

This term is a specialized linguistic concept used to describe a specific type of irregular inflection. It occurs when a language fills a gap in a grammatical paradigm using a word from an entirely different root, rather than applying a standard rule of modification. The most prominent example in English is the verb "go," where the past tense "went" is derived from a separate historical root ("wend") rather than a modification of "go."

Because it is a technical term of art in linguistics, it is almost exclusively found in academic papers, grammar textbooks, and philological discussions. It should not be confused with "supplementation" in a general sense, as "suppletion" refers specifically to the morphological replacement of a root within a paradigm.