peeper

noun6

1. •
   Someone who peeps; a spy.

   • Who's there? peepers, intelligencers, eavesdroppers? — 1604
2. •
   A peeping tom.
3. •
   (slang, disapproving) A private detective.

   • So you go to see this peeper, this Marlowe. That was your mistake. — 1944
4. •
   [in the plural] (informal) The eye.

   • Check out the gorgeous peepers on that guy!
5. •
   An animal, such as some frogs, having a shrill, high-pitched call.
6. •
   (informal) A chicken just breaking the shell; a young bird.