'associational' originates from Latin, specifically the word 'associatio' (from 'associare'), where 'ad-' (often assimilated) meant 'to/toward' and 'socius' meant 'companion' or 'ally'.

'associational' changed from Latin 'associatio' to Old French 'association' and Middle English 'associacioun' (or 'association'), and the modern English adjective 'associational' was formed by adding the adjectival suffix '-al' to 'association'.

Initially it referred to 'the act of joining or fellowship' (the noun 'association'); over time the adjective form came to mean 'relating to an association' or 'relating to association/associative processes'.