1. [mid-16C+] an eye, usu. in pl.
2. [late 17C–19C] a looking-glass, a mirror.
3. [early 18C] glass, e.g. a window.
4. [late 18C–mid-19C] a telescope, a spy-glass.
5. [early 19C] in pl., spectacles.
6. [late 19C+] a police officer; a security officer, e.g. in a hotel.
7. [20C+] (US) in pl., sunglasses.
8. [1940s] a private investigator, with implications of voyeurism.
9. [1940s+] a Peeping Tom, a voyeur.
[late 18C–1940s] a black eye; in pl., a pair of black eyes.
[late 19C-1910s] to keep a lookout; to look wide-eyed.
[19C+] a black eye; usu. in pl.