Elbow is the joint in the middle of your arm that lets you bend it. Without elbows, you couldn't touch your own face, throw a ball, or lift food to your mouth. The elbow connects your upper arm bone to the two bones in your forearm, creating a hinge that moves mostly in one direction, like a door.

The bony point you can feel on the outside of your elbow is actually the end of your upper arm bone. That spot has almost no padding between bone and skin, which is why bumping it feels so strange and tingly (people call this hitting your “funny bone,” though there's nothing funny about that sharp, electric sensation).

The word also describes sharp angles that look like bent arms. A pipe might have an elbow where it turns a corner. A hiking trail with a sharp turn might have an elbow in it.

To elbow someone means to push them with your elbow, often to get their attention or to squeeze through a crowd. Someone might elbow their way to the front of a line, which suggests pushiness. If you need elbow room, you need more space to move around comfortably. Elbow grease is an old-fashioned phrase meaning hard physical work and effort, the kind that makes you tired and sweaty.