A ledge is a narrow, flat surface that sticks out from a wall, cliff, or building, like a shelf built into the side of something. Mountain climbers sometimes rest on rocky ledges jutting out from cliffsides. Birds build nests on window ledges. In older buildings, you might see decorative stone ledges running along the outside walls.

Picture a narrow shelf on a cliff face, just wide enough to stand on, with empty space above and below. That's a ledge.

Around the house, a window ledge (also called a windowsill) is the flat surface at the bottom of a window frame where people sometimes place plants or decorations. Fireplace mantels work like ledges too. In geology, a rocky ledge might be visible along a hillside where harder rock resists erosion better than the softer rock around it.

People use the phrase “out on a ledge” to describe taking a risk or putting yourself in a vulnerable position, like when you argue for an unpopular opinion that your friends might disagree with.