skim milk vs milk

skim milk and milk both are nouns.

Word	Noun	Adjective	Verb	Adverb
skim milk	Yes	No	No	No
milk	Yes	No	Yes	No

As nouns, milk is a hypernym of skim milk; that is, milk is a word with a broader meaning than skim milk:

skim milk: milk from which the cream has been skimmed
milk: a white nutritious liquid secreted by mammals and used as food by human beings

skim milk (noun)	milk (noun)
milk from which the cream has been skimmed	produced by mammary glands of female mammals for feeding their young
	a white nutritious liquid secreted by mammals and used as food by human beings
	any of several nutritive milklike liquids

skim milk (verb)	milk (verb)
	take milk from female mammals
	add milk to
	exploit as much as possible