'associator' originates from English, formed from the verb 'associate' plus the agentive suffix '-or'; 'associate' ultimately comes from Latin 'associare' (from ad- + sociāre), where 'socius' meant 'companion'.

'associator' developed from Middle English and Old French forms of 'associate' (e.g. Old French 'associer' / Middle English 'associate'), which trace back to Late Latin 'associare' and Latin 'socius'; the modern English agent noun formation produced 'associator'.

Initially it meant 'one who joins or is joined/partner' (an agent noun from 'associate'); over time it has also acquired specialized technical senses (for example, in algebra and category theory, meaning a quantity or natural isomorphism measuring or expressing associativity).