A show-off is someone who keeps displaying how clever, skilled, rich, or good-looking they are, so other people will notice and admire them. It is almost always disapproving: we do not usually call someone a show-off as a compliment. The noun comes from the phrasal verb show off (to behave that way). Informal. You might say Don't be such a show-off to a friend who will not stop. What they show off with can be anything: a new phone, a trick on a bike, a big English word. Though actually, the same person may only be excited or proud; show-off puts a cold reading on it, as if the point was the audience.