The word pig comes from Old English, a germanic language spoken in England during the early middle ages. After William the Conqueror successfully invaded England in 1066 the language of upper classes of England became Anglo-Norman, an old form of French.

Because the English upper classes were speaking Norman many of the culinary terms such as pork, beef, and poultry in modern English come from the Norman language.

But because animals would have been raised by common people they retained the Old English derived names such as pig, cow, chicken.

What’s really interesting is how the animal word is Germanic in origin but the food word is Romantic

Cow/beef

Sheep/mutton

Chicken/poultry

The reason is one of the byproducts of the Norman Conquest. The local English people raised cows, pigs, sheep, and chickens, but the nobles (mostly, if not entirely French) were the only ones who could afford to eat meat. They said boeuf, porc, mouton, and pouletrie.

https://ell.stackexchange.com/questions/32560/why-are-beef-a...