Rheumatism is an old-fashioned term for pain, stiffness, and swelling in the joints, muscles, or connective tissues of the body. When someone says their grandmother complains of rheumatism, she probably means her knees ache when she climbs stairs, or her fingers feel stiff and sore when she tries to open a jar.

Doctors today rarely use this word because it's too vague: it could describe many different conditions, from arthritis to lupus to fibromyalgia. Each of these has specific causes and treatments, so modern medicine prefers precise names. But rheumatism remains common in everyday conversation, especially among older people describing aches and pains.

Cold, damp weather often makes rheumatic pain worse, which is why you might hear someone say the rain makes their rheumatism act up. Think of it as a general term for persistent joint and muscle pain that can make movement uncomfortable, especially as people age.