'arbitrager' originates from French, specifically the word 'arbitrage' with the agent suffix '-er', where 'arbitrage' referred to the act of arbitration or settlement (and later to financial arbitration).

'arbitrage' came into English from French 'arbitrage', which itself relates to Latin 'arbiter' meaning 'judge' or 'authority'; the English agent noun 'arbitrager' developed by adding the English/French-derived agent suffix '-er' to 'arbitrage'.

Initially it was associated with 'the act of arbitrating or settling disputes'; over time, especially in financial contexts, it evolved to mean 'a person who profits from price differences across markets'.