1400-50;late Middle English < Latinassociātus joined to, united with (past participle of associāre), equivalent to as-as- + soci- (see social) + -ātus-ate1; compare Anglo-Frenchassocier (v.), associé (noun)
mid-15c., from Latin associatus past participle of associare "join with," from ad- "to" (see ad-) + sociare "unite with," from socius "companion" (see social (adj.)). Related: Associated; associating. Earlier form of the verb was associen (late 14c.), from Old French associier "associate (with)."