(grammar) More loosely, the use of unrelated (or distantly related) words for semantically related words which may not share the samelexical category, such asfather/paternal orcow/bovine, normally referred to ascollateral adjectives.
Strictly speaking,suppletion in linguistics refers only to inflection, such asgood /better, which are both adjectives, and this is the most frequent use. It is also used in the looser sense of semantic relations without etymological relations (or with distant etymological relations) such asfather /paternal, where these are noun/adjective.[1][2] However, this latter use is significantly less common and may be considered incorrect. The termsuppletion is particularly used to contrast these phenomena with phonologically conditioned irregularities likeman /men, where both parts are derived by sound changes from an originally regular paradigm.
^Paul Georg Meyer (1997)Coming to know: studies in the lexical semantics and pragmatics of academic English, p. 130: "Although many linguists have referred to [collateral adjectives] (paternal, vernal) as 'suppletive' adjectives with respect to their base nouns (father, spring), the nature of ..."
^Aspects of the theory of morphology, by Igor Melʹčuk,p. 461
