'unbutton' originates from Middle English, specifically the prefix 'un-' meaning 'not' or 'opposite of' and the word 'button', which comes from Old French 'bouton', meaning 'knob' or 'button'.

'unbutton' changed from the Middle English word 'unbotenen' and eventually became the modern English word 'unbutton'.

Initially, it meant 'to undo a button', and this meaning has largely remained the same in modern usage.