'unsympathetic' originates from the prefix 'un-' meaning 'not' and the word 'sympathetic', which comes from the Greek word 'sympathetikos', where 'sym-' meant 'together' and 'pathos' meant 'feeling'.

'sympathetikos' transformed into the Latin word 'sympathicus', and eventually became the modern English word 'sympathetic', with 'un-' added to form 'unsympathetic'.

Initially, it meant 'not sharing feelings', and this meaning has largely remained the same in modern usage.