peephole

[ peep-hohl ]

/ ˈpipˌhoʊl /

a small hole or opening through which to peep or look, as in a door.

Origin of peephole

First recorded in 1675–85; peep¹ + hole

peep, peep show, peep sight, peepee, peeper, peephole, peeping tom, peeps, peepshow, peepul, peer

It may have been the direct influence from her peep-hole on Olympus of Sappho's own Aphrodite.

Yellowstone Nights |Herbert Quick
So I stepped in, making a peep-hole to see through, and lay in wait.

Lost in the Jungle |Paul Du Chaillu
"I'll show you how," added Kitty, taking her turn at the peep-hole.

Just Sixteen. |Susan Coolidge
He replied, on the same system, by passing his lantern in front of the peep-hole.

The World's Greatest Books, Vol VIII |Arthur Mee and J.A. Hammerton, Eds.

Carefully, so as not to make noise, he stole to the peep-hole and applied his eye.

The Day of the Beast |Zane Grey

peephole

/ (ˈpiːpˌhəʊl) /

a small aperture, such as one in the door of a flat for observing callers before opening