convention

LINGUISTICS uses this term in its general sense – referring to any accepted practice in the use of LANGUAGE (e.g. the ‘convention’ of using certain formulae upon leave-taking), or in developing a MODEL of language (e.g. it is ‘conventional’ to transcribe PHONEMES using // brackets). But there is also a restricted sense, where it refers to the ARBITRARY nature of the relationship between linguistic EXPRESSIONS and their MEANINGS: one says that the relationship between the LEXICAL ITEM table and the thing ‘table’ is conventional, the term here being used in a traditional philosophical sense which dates from Plato.