Traditional
This is a macaronic (more than one language in the same song) 15th century Christmas carol that describes the ancient tradition of sacrificing a boar and presenting its head at a Yuletide feast. This version is based on a version published in 1521 in Wynkyn de Worde’s “Christmasse Carolles”.
The tradition itself is probably a Saxon one and therefore pagan. In the Dark Ages and pre-Christian Europe the boar sacrifice was made at the winter solstice to implore the gods to show favour in the new year, with the year beginning at the solstice itself.
Source: https://en.wikipedia.org/wiki/Boar’s_Head_Carol and see our Latin page for more about Latin.