'illegitimacy' originates from Latin, specifically the word 'illegitimus,' where 'in-' meant 'not' and 'legitimus' meant 'lawful.'

'illegitimus' transformed into the Medieval Latin word 'illegitimitas,' and eventually became the modern English word 'illegitimacy.'

Initially, it meant 'not lawful or not in accordance with the law,' but over time it evolved into its current meaning of 'being born out of wedlock or not conforming to accepted standards.'