Pound on a door is an expression used to describe the act of banging on a door with one's fists in order to make a loud noise and attract attention. It is often used as a way to gain entry into a locked or closed door, or to alert someone inside that someone is outside. The term can also be used figuratively to describe a situation where someone is persistently trying to get someone else's attention. The crossword solution for this term is BANG, which is a four-letter word meaning to hit something with force.