What is "arthrodia"

Arthrodia \Ar*thro"di*a\, n. [NL., fr. Gr. ?, fr. ? well articulated; 'a`rqron a joint + ? shape.] (Anat.) A form of diarthrodial articulation in which the articular surfaces are nearly flat, so that they form only an imperfect ball and socket.

n. (context anatomy English) A form of diarthrodial articulation in which the articular surfaces are nearly flat, so that they form only an imperfect ball and socket joint.