eye vs nictitating membrane

eye and nictitating membrane both are nouns.

Word	Noun	Adjective	Verb	Adverb
eye	Yes	No	Yes	No
nictitating membrane	Yes	No	No	No

eye (noun)	nictitating membrane (noun)
a small hole or loop (as in a needle)	a protective fold of skin in the eyes of reptiles and birds and some mammals
the organ of sight
good discernment (either visually or as if visually)
attention to what is seen
an area that is approximately central within some larger region

eye (verb)	nictitating membrane (verb)
look at