'assignor' originates from Anglo-French, specifically the word 'assignour,' where 'assigner' meant 'to assign' and the suffix '-or' indicated a person who does an action.

'assignour' transformed into the Middle English word 'assignour,' and eventually became the modern English word 'assignor.'

Initially, it meant 'a person who assigns or transfers something,' and this meaning has remained the same in modern usage.