'unsanitary' originates from the prefix 'un-' meaning 'not' and the word 'sanitary', which comes from the Latin 'sanitarius', meaning 'pertaining to health'.

'sanitarius' transformed into the English word 'sanitary', and with the addition of the prefix 'un-', it became 'unsanitary'.

Initially, 'sanitary' meant 'pertaining to health', and with the prefix 'un-', it evolved to mean 'not clean or hygienic'.