temporomandibular joint (TMJ) disorder, dysfunction of the temporomandibular joint, marked by a clicking or grinding sensation in the joint and often by pain in or about the ears, tinnitus, tiredness, slight soreness of the jaw muscles on waking, and stiffness of the jaw or actual trismus. Numerous causes have been proposed, such as mandibular overclosure, stress, and lesions of the joint. Also called TMJ disorder.
