aperture vs pupil

aperture and pupil both are nouns.

Word	Noun	Adjective	Verb	Adverb
aperture	Yes	No	No	No
pupil	Yes	No	No	No

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

aperture: a natural opening in something
pupil: the contractile aperture in the center of the iris of the eye; resembles a large black dot

Other hyponyms of aperture include micropyle, pore, stoma, stomate.

aperture (noun)	pupil (noun)
an man-made opening; usually small	the contractile aperture in the center of the iris of the eye; resembles a large black dot
a device that controls amount of light admitted	a learner who is enrolled in an educational institution
a natural opening in something	a young person attending school (up through senior high school)