Rheumatism is a wide, rather old word for long-lasting pain and stiffness in the joints or muscles — the kind that makes it hard to stand up, or that feels worse on cold, wet days. Older people still say “my rheumatism is playing up,” as if it were one familiar enemy. Though actually, doctors today hardly use the word, because it bundles together many different problems we now name more exactly: worn joints, rheumatoid arthritis, gout, and others. The name comes from an old picture of the body in which a watery stuff (a “rheum”) was thought to flow into the joints and cause the ache. That is not how medicine thinks now, but the word stayed. It is not slang, and it is not rude; it just sounds a little dated in a clinic, and a little homely in the family.