'assignor' originates from Latin (via Old French and Middle English), specifically the verb 'assignare' (Late Latin) / Old French 'assigner', where 'ad-' meant 'to/toward' and 'signare' meant 'to mark, sign'.

'assignor' developed from the Late Latin verb 'assignare' → Old French 'assigner' → Middle English forms like 'assignen'/'assigne' → modern English 'assign' with the agentive suffix '-or' forming 'assignor'.

Initially related to 'marking out' or 'allotting' (the act of assigning), the sense shifted to denote the person who performs the transfer — specifically a person who transfers rights or property (the modern legal/contract sense).