The A.M.A. is a large organisation in the United States for doctors and people who do medical research. The letters stand for American Medical Association. Members are mostly physicians; the group speaks for them in public, talks to the government about health, and publishes a well-known medical journal. It is a formal name. You meet it in US news and textbooks more than in everyday chat, and when people say it they usually speak each letter: “the A-M-A.” It is an American body, not a world one. The UK has a similar group called the B.M.A. (British Medical Association). Taiwan has its own doctors’ associations; this English name points to the US one. Though actually, on the internet AMA often means “ask me anything,” which is just a chat invitation and has nothing to do with doctors.