gasket vs head gasket

gasket and head gasket both are nouns.

Word	Noun	Adjective	Verb	Adverb
gasket	Yes	No	No	No
head gasket	Yes	No	No	No

As nouns, head gasket is a hyponym of gasket; that is, head gasket is a word with a more specific, narrower meaning than gasket:

gasket: seal consisting of a ring for packing pistons or sealing a pipe joint
head gasket: a gasket to seal a cylinder head

Other hyponyms of gasket include O ring.

gasket (noun)	head gasket (noun)
seal consisting of a ring for packing pistons or sealing a pipe joint	a gasket to seal a cylinder head