Definition of "eyehole"

eyehole

noun
plural eyeholes
1. The hole to which the viewer places his or her eye in a device such as a telescope.
2. The hole in a helmet, skull, etc. corresponding to the position of the eye.
  Quotations
  Eyeholes in a paper bagGreatest lay I ever had
  1997, Placebo (lyrics and music), “Nancy Boy”