A crevice is a narrow crack or opening, especially in rock or a wall. When you're climbing on boulders and notice a thin gap between two rocks, that's a crevice. Mountain climbers often wedge their fingers and toes into crevices to pull themselves up steep rock faces.

Crevices form naturally when rock splits or shifts over time, or when concrete cracks and separates. You might find crevices in an old stone wall, between sidewalk sections, or along a cliff face. Animals like lizards, spiders, and small snakes often hide in crevices to stay cool and safe from predators.

The word can describe any narrow gap that's deeper than it is wide. If you drop a coin and it falls into a crevice between couch cushions, you know you'll have to dig around to fish it out. Scientists studying glaciers worry about dangerous cracks in the ice called crevasses, which are much larger and can be deep enough to swallow a person.

Think of a crevice as nature's hiding place: too narrow to see into easily, but deep enough to matter. When something disappears into a crevice, getting it back can take patience and careful work.