Source : Webster's Revised Unabridged Dictionary (1913)

Peeper \Peep"er\, n.
   1. A chicken just breaking the shell; a young bird.

   2. One who peeps; a prying person; a spy.

            Who's there? peepers, . . . eavesdroppers? --J.
                                                  Webster.

   3. The eye; as, to close the peepers. [Colloq.]

Source : WordNet®

peeper
     n 1: a viewer who enjoys seeing the sex acts or sex organs of
          others [syn: {voyeur}, {Peeping Tom}]
     2: an informal term refering to the eye
     3: an animal that makes short high-pitched sounds