pupil

nouns

a learner who is enrolled in an educational institution
educatee, pupil, student
the contractile aperture in the center of the iris of the eye; resembles a large black dot
pupil
is derived from
pupillary
is a part of
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
iris
is a type of (narrower)
a natural opening in something
aperture
a young person attending school (up through senior high school)
pupil, school-age child, schoolchild