'associativity' originates from Latin, specifically from the root 'socius' and the verb 'sociāre' (Late Latin 'associare'), where 'soci-' meant 'companion' (or 'ally') and the suffix '-ity' comes from Latin '-itas' denoting a state or quality.

'associativity' developed from Late Latin 'associativus' / Latin 'associatio' (meaning 'a joining together'), passed into Middle French/Medieval Latin forms and then into English as 'association' and the adjective 'associative', from which the noun 'associativity' was formed (English).

Initially it referred broadly to 'the action or condition of joining or associating things or people'; over time it became specialized in mathematics to denote the specific property of operations where grouping does not affect outcome.