'untrue' originates from Old English, specifically the word 'untrēowe,' where 'un-' meant 'not' and 'trēowe' meant 'faithful or true.'

'untrēowe' transformed into the Middle English word 'untrewe,' and eventually became the modern English word 'untrue.'

Initially, it meant 'not faithful or loyal,' but over time it evolved to also mean 'not in accordance with fact or reality.'