To look briefly and quickly
A quick look
A peeping sound
To look cautiously
To make a peeping sound
I ain't heard a peep out of his room since.
Or I heard the peep of the young when I could not see the parent bird.
She crossed the living room and paused at the door, looking through the peep hole.
She crossed to it and peered through the peep hole, surprised to see Jonny's caramel features and black eyes.
L is the producer-shaft, with an iron casing B and peep holes B 1 to B4, passing through the brick lining M.