1. To peer, glimpse, or glance through (something) quickly, shyly, or inconspicuously. I peeped through the curtains to see if the man was still lurking outside our house. I looked over at the door and could see a small child peeping through at me.

2. To be revealed partially through or from behind something. I went the whole day without realizing that my bra was peeping through my dress. I tried to cover up the graffiti with black paint, but there was still a bit of color peeping through.