If you are disdainful, you show that you do not respect someone or something, because you have already decided they are not important enough, or not good enough. The feeling sits above the other person: you look down. A disdainful look, a disdainful smile, a disdainful remark — the word likes to sit on the face and on the voice. It is stronger than simply not liking something. You can dislike a meal and still treat it as ordinary food; disdain says the thing is beneath you. Though actually, people also stretch it for any cold, superior manner, even when the person is really just shy, tired, or trying to keep a distance. The word is not slang. You will hear it in stories, in news, and in everyday talk about attitude, and it often sounds a little critical of the person who feels it, not only of the person they look down on.