A cranny is a small, narrow opening or crack, especially in a wall, rock, or other solid surface. When you hear the phrase every nook and cranny, it means every tiny space or hidden spot in a place. If you're searching for a lost toy, you might look in every nook and cranny of your room: behind the dresser, under the bed, in the closet corners, anywhere something small could hide.

Crannies are the kinds of spaces where things accidentally slip into or where small creatures might shelter. A lizard might disappear into a cranny between two rocks. Seeds can take root in the crannies of stone walls.

The word often appears with nook, its close companion. While the two words mean similar things, cranny emphasizes the narrow, crack-like quality of the space. Think of the tiny gaps between floorboards, the thin spaces where a wall meets the ceiling, or the slim crevices in tree bark where insects hide. When you really want to find something or clean thoroughly, those crannies are exactly the spots you can't afford to miss.