'unreflective' originates from the prefix 'un-' meaning 'not' and the word 'reflective', which comes from Latin 'reflectere', where 're-' meant 'back' and 'flectere' meant 'to bend'.

'reflectere' transformed into the Old French word 'reflecter', and eventually became the modern English word 'reflective'. The prefix 'un-' was added to form 'unreflective'.

Initially, 'reflective' meant 'bending back', but over time it evolved into its current meaning of 'thoughtful'. 'Unreflective' negates this meaning.