'inadvertently' originates from Latin, specifically the word 'inadvertentem,' where 'in-' meant 'not' and 'advertentem' meant 'turning the mind to.' 'Neglected' originates from Latin, specifically the word 'neglectus,' where 'neg-' meant 'not' and 'legere' meant 'to pick up or choose.'

'inadvertentem' transformed into the French word 'inadvertent,' and eventually became the modern English word 'inadvertent.' 'Neglectus' transformed into the Old French word 'negliger,' and eventually became the modern English word 'neglect.'

Initially, 'inadvertent' meant 'not turning the mind to,' but over time it evolved into its current meaning of 'unintentional.' 'Neglect' initially meant 'not choosing or picking up,' and this meaning has largely remained the same in modern usage.