third eyelid vs haw

third eyelid and haw both are nouns.

Word	Noun	Adjective	Verb	Adverb
third eyelid	Yes	No	No	No
haw	Yes	No	Yes	No

As nouns, haw is a hyponym of third eyelid; that is, haw is a word with a more specific, narrower meaning than third eyelid:

third eyelid: a protective fold of skin in the eyes of reptiles and birds and some mammals
haw: the nictitating membrane of a horse

third eyelid (noun)	haw (noun)
a protective fold of skin in the eyes of reptiles and birds and some mammals	the nictitating membrane of a horse
	a spring-flowering shrub or small tree of the genus Crataegus

third eyelid (verb)	haw (verb)
	utter `haw'