Buster/ˈbʌstər/ Definition 1 of 5Pro Tip 1/2Negative Connotation Used to describe someone ruining fun, often disliked for this reason. Don't invite him; he's a total party buster. Pro Tip 2/2End of Activity Implies the activity ended because of the 'buster's' intervention. She's a game buster. When she loses, the game is over.