'unperceptive' originates from the prefix 'un-' meaning 'not' and the word 'perceptive', which comes from Latin 'perceptivus', meaning 'capable of perceiving'.

'perceptivus' transformed into the Old French word 'perceptif', and eventually became the modern English word 'perceptive', with 'un-' added to form 'unperceptive'.

Initially, 'perceptive' meant 'capable of perceiving', and 'unperceptive' has consistently meant 'not capable of perceiving'.