To skulk means to move around quietly and secretively, usually because you're up to no good or trying to avoid being noticed. When someone skulks around the edges of a playground instead of joining in, they're creeping along in the shadows, perhaps planning mischief or hiding from someone. A character in a mystery novel might skulk through dark hallways, pressed against walls and peeking around corners.

The word carries a sneaky, somewhat guilty feeling. You wouldn't say someone skulks into a surprise party they're throwing for a friend, even though they're being secretive. That's hiding with good intentions. But you would say a fox skulks around a henhouse, or that a student caught breaking rules might skulk away from the principal.

Skulking suggests lurking with bad intentions or embarrassment, slinking around rather than walking openly and confidently. When you have nothing to hide, you stride or stroll. When you're ashamed or plotting something, you skulk.