'unwarranted' originates from Middle English, specifically the word 'warrant,' where 'un-' meant 'not' and 'warrant' meant 'to authorize or justify.'

'warrant' transformed into the adjective 'unwarranted' by adding the prefix 'un-' to indicate the absence of justification or authorization.

Initially, it meant 'not authorized or justified,' and this meaning has largely remained the same in modern usage.