PMS is short for premenstrual syndrome. It is the mix of body feelings and mood changes that many women get in the days before their period starts — sore breasts, a swollen tummy, tiredness, spots, feeling low, or feeling easily angry. Not every woman gets it, and it is not the same every month. Doctors use the name; friends, magazines, and clinics use it too. It is everyday English now: a little medical, but not stiff. People sometimes joke about PMS when a woman is upset. That is unkind and often wrong — being angry is not proof of PMS, and the letters are not a free joke. The feelings are real. American and international English usually say PMS; British English has often said PMT for the same thing.