pupil vs iris

pupil and iris both are nouns.

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

pupil (noun)	iris (noun)
the contractile aperture in the center of the iris of the eye; resembles a large black dot	diaphragm consisting of thin overlapping plates that can be adjusted to change the diameter of a central opening
a learner who is enrolled in an educational institution	muscular diaphragm that controls the size of the pupil which in turn controls the amount of light that enters the eye; it forms the colored portion of the eye
a young person attending school (up through senior high school)	plants with sword-shaped leaves and erect stalks bearing bright-colored flowers composed of three petals and three drooping sepals