If someone is glum, they feel unhappy in a quiet, heavy way, and they do not feel like talking. The face often falls; they look as if a small cloud is sitting on them. It is not usually wild crying or a loud complaint. It is the mood of someone who has had bad news, or who is disappointed, and has gone still. You can call a person glum, or a look, or a silence. You would not normally call a rainy day glum — that is more gloomy. The word is a little old-fashioned and a little British, but people still use it, often with gentle teasing: “Don’t look so glum.” Though actually, it is milder than depressed, and shorter-lived than that word suggests. It is a mood on the face more than a medical state.