A dartboard is the round board you throw darts at in the game of darts. It hangs on a wall and is covered in numbered slices, with a small centre called the bullseye. You score by where the dart sticks. In Britain you will hear this word all the time in pubs and sports talk; it is ordinary, not fancy. Though actually the board is not a random pattern. The numbers sit in a fixed order so that a dart which just misses a high number often scores very little — that is part of the skill. The game is usually called darts, with an s. The thing on the wall is a dartboard, one word.