n. A small hole, opening, or glass, especially in a door, through which to look.
the GNU version of the Collaborative International Dictionary of English
n. A hole, or crevice, through which one may peep without being discovered.
The Century Dictionary and Cyclopedia
n. A hole or crevice through which one may peep or look.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a hole (in a door or an oven etc) through which you can peep
Word Usage
"SELLS VIDEO SURVEILLANCE EQUIPMENT: Well, if it was through the peephole, fortunately or unfortunately, there is a device called a peephole reverser."