Hi David, 

The first word that springs to mind for a boar in French is 'un sanglier' which technically is a wild boar.

Having researched the subject it looks like in English a boar refers to an intact (not castrated) adult male pig that is used for breeding purposes.

So it can get very complicated!

The terms, 'cochon' or 'porc' are normally used for male domestic pigs.

Hope this helps!