The Collaborative International Dictionary of English v.0.48:

Pupil \Pu"pil\, n. [F. pupille, n. fem., L. pupilla the pupil of
   the eye, originally dim. of pupa a girl. See Puppet, and
   cf. Pupil a scholar.] (Anat.)
   The aperture in the iris; the sight, apple, or black of the
   eye. See the Note under Eye, and Iris.
   [1913 Webster]

   Pin-hole pupil (Med.), the pupil of the eye when so
      contracted (as it sometimes is in typhus, or opium
      poisoning) as to resemble a pin hole. --Dunglison.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pupil \Pu"pil\, n. [F. pupille, n. masc. & fem., L. pupillus,
   pupilla, dim. of pupus boy, pupa girl. See Puppet, and cf.
   Pupil of the eye.]
   1. A youth or scholar of either sex under the care of an
      instructor or tutor.
      [1913 Webster]

            Too far in years to be a pupil now.   --Shak.
      [1913 Webster]

            Tutors should behave reverently before their pupils.
                                                  --L'Estrange.
      [1913 Webster]

   2. A person under a guardian; a ward. --Dryden.
      [1913 Webster]

   3. (Civil Law) A boy or a girl under the age of puberty, that
      is, under fourteen if a male, and under twelve if a
      female.
      [1913 Webster]

   Syn: Learner; disciple; tyro. -- See Scholar.
        [1913 Webster]

WordNet (r) 3.0 (2006):

pupil
    n 1: a learner who is enrolled in an educational institution
         [syn: student, pupil, educatee]
    2: the contractile aperture in the center of the iris of the
       eye; resembles a large black dot
    3: a young person attending school (up through senior high
       school) [syn: schoolchild, school-age child, pupil]

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "pupil":
   apprentice, auditor, autodidact, baby blues, banjo eyes, beginner,
   bright eyes, catechumen, clear eyes, cornea, disciple, educatee,
   eye, eyeball, eyelid, goggle eyes, inquirer, iris, learner, lens,
   lid, monitor, naked eye, neophyte, nictitating membrane, novice,
   oculus, optic, optic nerve, orb, organ of vision, peeper, popeyes,
   praepostor, prefect, retina, saucer eyes, scholar, schoolboy,
   schoolgirl, sclera, self-taught person, starry orbs, student,
   studier, trainee, tyro, unaided eye, visual organ



Bouvier's Law Dictionary, Revised 6th Ed (1856):

PUPIL, civil law. One who is in his or her minority. Vide. Dig. 1, 7; Id.
26, 7, 1, 2; Code, 6, 30, 18; Dig. 50, 16, 239. One who is in ward or
guardianship.