Elbow (noun)

1. The joint connecting the upper arm and the forearm.
2. The protruding bend in a pipe or conduit.
3. The sharp or curved bend in a river or road.

Origin:

From middle english elboghe, from old english elboga, from proto-germanic *albōgaz ("elbow"), from proto-indo-european *h₁el- ("to bend") + *bōg- ("bending, bow").

Examples:

1. He injured his elbow while playing.
2. She leaned on her elbow.
3. He cleaned behind the refrigerator by reaching his arm through the elbow in the pipe.
4. The elbow of the river made a sharp turn.
5. He bent his elbow to lift the weight.