What does bastard mean?
The word ‘bastard’ comes from the old french ‘fils de bast’ which became ‘bast-art’ and the modern ‘bâtard’. ‘bast’ means packsaddle in old French.
When poor young men were travelling they would sleep on their packsaddle in the stable where they might get up to hanky panky with the barmaid.
A child would be born and noone would know who the father was so the baby would be called ‘son of a packsaddle’ (fils de bast).
Similarly, the expression ‘son of a gun’ comes from maritime history where the lower deck by the guns would be cordoned off to make into a makeshift hospital for pregnant women who would give birth next to the cannons. If no sailor owned up to being the father then they would write on the birth certificate: ‘son of a gun’.