Other forms: peepholes
A peephole is the tiny lens in a front door for seeing who knocked. Look through the peephole, a brass peephole, fit a peephole.
The lens is a fisheye, which is why it shows the whole doorstep and makes everybody look strange. It works one way only because of the light: it is bright outside and dark within, so nobody can see back in unless you light the hall.
1nounpeepholeThe tiny lens in a front door for seeing who knocked.
“Before opening the door, she looked through the peephole to see who was there.”
peephole is an opening.
Peep plus hole, recorded from the sixteenth century.
From peep + hole.
Etymology from Wiktionary, CC BY-SA