| Noun | 1. | tendinitis - inflammation of a tendon inflammation, redness, rubor - a response of body tissues to injury or irritation; characterized by pain and swelling and redness and heat lateral epicondylitis, lateral humeral epicondylitis, tennis elbow - painful inflammation of the tendon at the outer border of the elbow resulting from overuse of lower arm muscles (as in twisting of the hand) tendonous synovitis, tendosynovitis, tenosynovitis - inflammation of a tendon and its enveloping sheath |