'wager' originates from Old North French, specifically the word 'wagier', where the root referred to a 'pledge' or 'security'.

'wager' changed from Old North French 'wagier' into Middle English (appearing as 'wager' or similar spellings) and eventually became the modern English word 'wager'.

Initially, it meant 'to give a pledge' or 'to pledge (something)'; over time it evolved into the current meaning 'to bet or stake something on an outcome'.