arcus vs cornea

arcus and cornea both are nouns.

Word	Noun	Adjective	Verb	Adverb
arcus	Yes	No	No	No
cornea	Yes	No	No	No

As nouns, cornea is a hypernym of arcus; that is, cornea is a word with a broader meaning than arcus:

arcus: a whitish deposit in the shape of an arc that is sometimes seen in the cornea
cornea: the transparent dome-shaped anterior portion of the outer covering of the eye; it covers the iris and pupil and is continuous with the sclera

arcus (noun)	cornea (noun)
a whitish deposit in the shape of an arc that is sometimes seen in the cornea	the transparent dome-shaped anterior portion of the outer covering of the eye; it covers the iris and pupil and is continuous with the sclera