What is the definition or description of: synovitis?

Joint inflammation : The synovial membrane is the lining of a joint and synovitis is inflammation of that lining. It can cause joint pain, swelling, and stiffness. When inflamed, the lining will create excessive joint fluid, causing swelling and increased joint pressure. The lining can also become thickened and cause apparent joint enlargement. Commonly associated with arthritis and joint infection.