In the sense students usually meet, anorexia is a serious mental illness in which a person is terrified of gaining weight and so eats far too little — often while still seeing themselves as “too heavy.” The full medical name is anorexia nervosa. Doctors, though actually, also use anorexia in an older, wider way: simply a loss of appetite, for example when you are very ill and do not want food. That second use is closer to the Greek pieces of the word. In everyday English, though, anorexia almost always means the eating illness, not “I skipped lunch.” It is a clinical word. Speak about it gently. It is not a diet, not a look, and not a joke about being thin. A person can have anorexia and still not look the way rumours say they “should.”