yak butter vs butter

yak butter and butter both are nouns.

Word	Noun	Adjective	Verb	Adverb
yak butter	Yes	No	No	No
butter	Yes	No	Yes	No

As nouns, butter is a hypernym of yak butter; that is, butter is a word with a broader meaning than yak butter:

yak butter: butter made from yaks' milk
butter: an edible emulsion of fat globules made by churning milk or cream; for cooking and table use

yak butter (noun)	butter (noun)
butter made from yaks' milk	an edible emulsion of fat globules made by churning milk or cream; for cooking and table use
	a fighter who strikes the opponent with his head

yak butter (verb)	butter (verb)
	spread butter on