Noun, pl. elbows
1. In primates, including humans, the elbow joint is the synovial hinge joint between the humerus in the upper arm and the radius and ulna in the forearm which allows the hand to be moved towards and away from the body. The superior radioulnar joint shares joint capsule with the elbow joint but plays no functional role at the elbow. The elbow region includes prominent landmarks such as the olecranon (the bony prominence at the very tip of the elbow), the elbow pit, and the lateral and medial epicondyles. (wikipedia.org)
2. The joint between the upper arm and the forearm. (wiktionary.org)
Word origin: Old English elnboga, from Germanic, corresponding to ell + bow. Cognate with Dutch elleboog, German Ellbogen.