diarthrosis (synovial joint) n.
a freely movable joint. The ends of the adjoining bones are covered with a thin cartilaginous sheet, and the bones are linked by a ligament (capsule) lined with synovial membrane, which secretes synovial fluid (see illustration). Such joints are classified according to the type of connection between the bones and the type of movement allowed. See arthrodic joint, condylarthrosis, enarthrosis, ginglymus, saddle joint, trochoid joint.