unison: [16] Unison originated as a musical term, denoting ‘of the same sound’. It comes via Old French unison from late Latin ūnisonus, a compound adjective formed from ūnus ‘one’ and sonus ‘sound’ (source of English sound). The metaphorical sense ‘agreement, concord’ emerged in the 17th century. => sound[unison etymology, unison origin, 英语词源]