A medical term for a ball-and-socket joint; a type of articulation that permits movement in any direction within a sphere.
From Greek 'en-' (in) + 'arthron' (joint) + '-osis' (condition, state). Standard anatomical terminology coined from Classical Greek roots for describing joint structure.
The word itself describes the structure—the ball (head of the bone) sits nested 'in' a socket, giving it total rotational freedom. It's why your shoulder is so flexible but also why it dislocates more easily than your elbow.
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