'unmask' originates from the prefix 'un-' meaning 'not' or 'opposite of' and the word 'mask', which comes from the Middle French 'masque', meaning 'covering for the face'.

'masque' transformed into the English word 'mask', and eventually combined with the prefix 'un-' to form the modern English word 'unmask'.

Initially, it meant 'to remove a mask', but over time it evolved into its current meaning of 'to reveal the true nature or identity'.