hinge joint

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A joint, such as the elbow, in which a convex part of one bone fits into a concave part of another, allowing motion in only one plane.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a freely moving joint in which the bones are so articulated as to allow extensive movement in one plane
• noun a joint allowing movement in one plane only