'inattentiveness' originates from the Latin word 'inattentus,' where 'in-' meant 'not' and 'attentus' meant 'attentive.'

'inattentus' transformed into the Old French word 'inattentif,' and eventually became the modern English word 'inattentive' through Middle English.

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