Webster’s Revised Unabridged Dictionary · 1913
Peeper
Peep′er (pēp′ẽr), 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.]