'associationist' originates from English, specifically the word 'association' combined with the suffix '-ist', where 'association' ultimately comes from Latin 'associare' (from 'ad-' meaning 'to' and 'socius' meaning 'companion' or 'ally') and the suffix '-ist' derives from Greek '-istēs' via Latin/French meaning 'agent' or 'follower'.

'associationist' developed in modern English by adding the agent suffix '-ist' to 'association' (Middle English 'associacioun' < Old French/Medieval Latin 'associatio' < Latin 'associare'), resulting in the form used in the 19th and 20th centuries and retained in contemporary English.

Initially, formations with 'association' and '-ist' could mean 'one who joins or forms associations'; over time the term came to be used more specifically for 'a proponent of associationism (in psychology)' and also for 'a member of an association'.