1. to be inside of something and take a look out. A pair of glimmering eyes peeked out of the darkened room at the two people standing at the door. I peeked out of my room at the eerie shadows in the hallway. Jerry peeked out of the bathroom to see if anyone was looking.
2. [for a little bit of something] to be revealed with the rest concealed within. A bit of white skin peeked out beneath his pants cuff.