Synovitis and Tendonous synovitis

Synovitis noun - Inflammation of the synovial membrane that lines a synovial joint; results in pain and swelling.

Tendonous synovitis and synovitis are semantically related. In some cases you can replace phrase "Tendonous synovitis" with "Synovitis", this terms are similar.

Tendonous synovitis noun - Inflammation of a tendon and its enveloping sheath.

Synovitis and tendonous synovitis are semantically related. You can use "Synovitis" instead a noun phrase "Tendonous synovitis".