'bastardy' originates from Old French, specifically the word 'bastardise,' where 'bastard' meant 'illegitimate child.'

'bastardise' transformed into the Middle English word 'bastardie,' and eventually became the modern English word 'bastardy'.

Initially, it meant 'the state of being a bastard,' but over time it evolved into its current meaning of 'the condition of being born to parents not married to each other.'