'unethical' originates from the prefix 'un-' meaning 'not' and the word 'ethical', which comes from the Greek word 'ethikos', meaning 'moral'.

'ethikos' transformed into the Latin word 'ethicus', and eventually became the modern English word 'ethical'. The prefix 'un-' was added to form 'unethical'.

Initially, 'ethical' meant 'pertaining to character', but over time it evolved into its current meaning of 'conforming to accepted standards of morality'.