Any of the articulations or joints in a leg.
2A joint in the leg of a man-made object such as piece of furniture, tripod, etc.
3A joint of meat consisting of (a portion of) the leg of an animal; (also) a large piece of meat which has been removed from around a leg bone and then rolled and secured with string prior to cooking.
Early 18th century; earliest use found in The London Gazette. From leg + joint.