eyehole

noun

1. The hole to which the viewer places his or her eye in a device such as a telescope.

   “Holonym: eyepiece”

2. The hole in a mask, helmet, or costume corresponding to the position of the eye, allowing the eye to look through it.

   “Eyeholes in a paper bag Greatest lay I ever had”

3. The hole in the face where the eye resides.

   “Meronyms: eye socket (bony orbit), orbital cavity, cranial orbit, orbit”