This combining form literally means flowing water; when used in medical terms, it refers to connective tissue.

The correct answer is rheumatism.

Rheumatism refers to all the conditions that cause chronic pain affecting the joints and/or connective tissue. It is not the term that describes any specific disorder, but it covers many different conditions such as capsulitis, back pain, neck pain, osteoarthritis. The study of this disorders is called rheumatology.