Bastard likely comes from Old French fils de bast, meaning 'packsaddle son' — a child conceived on a makeshift bed rather than in wedlock.
A person born to parents who are not married to each other; also a general term of abuse.
From Old French bastard, probably from fils de bast, meaning 'packsaddle son,' a crude reference to a child conceived on an improvised bed (a packsaddle used as a mattress) rather than in the marriage bed. The bast element comes from Germanic *banstiz, but the French derivation via bast (packsaddle) is more widely accepted. Key roots: bast (Old French