'bargainer' originates from English, formed from the noun 'bargain' plus the agent suffix '-er', where 'bargain' itself originated from Old French 'bargaigne' (or Old French verb 'bargaigner').

'bargain' changed from the Old French word 'bargaigne' and entered Middle English as 'bargain'; the agent-forming suffix '-er' was later added in English to create 'bargainer', which became the modern English word 'bargainer'.

Initially, 'bargain' referred to a contract or agreement (and related acts of trade); over time its related agent form 'bargainer' came to mean specifically 'one who negotiates terms' and also 'one who seeks good deals'.