'unobservant' originates from the prefix 'un-' meaning 'not' and the word 'observant', which comes from Latin 'observare', meaning 'to watch over'.

'observare' transformed into the Old French word 'observer', and eventually became the modern English word 'observe', from which 'observant' and subsequently 'unobservant' were derived.

Initially, 'observare' meant 'to watch over', and 'unobservant' evolved to mean 'not paying attention'.