'appositional' originates from Latin, specifically the word 'appositio', where 'ad-' (appearing as 'ap-') meant 'to, toward' and 'ponere' meant 'to place'.

'appositional' developed from the noun 'apposition', which came into English via Late Latin 'appositio' (and Old French apposition) and then Middle English 'apposition'; the adjective form 'appositional' was later formed from this noun.

Initially it meant 'a placing near or beside'; over time the term became specialized in grammar to mean 'placement of a noun phrase next to another for identification or explanation', and the adjective now means 'relating to that placement'.