Merriam-Webster's Word of the Day for June 26, 2024 is: zero-sum \ZEER-oh-SUM\ adjective Zero-sum describes something, such as a game, mentality, or situation, in which any gain corresponds directly with an equivalent loss. // Dividing up the budget is a zero-sum game. [See the entry >](https://www.merriam-webster.com/dictionary/zero-sum) Examples: “Domestic migration is zero-sum, meaning a loss of college graduates prized by local officials and tax collectors in Washington or San Francisco can be a gain for Kansas City or Orlando.” — Josh Katz, The New York Times, 15 May 2023 Did you know? Does [game theory](https://www.britannica.com/science/game-theory) sound like fun? It can be—if you are a mathematician or economist who needs to analyze a competitive situation in which the outcome is determined by the choices of the players and chance. Game theory was introduced by mathematician [John von Neumann](https://www.britannica.com/biography/John-von-Neumann) and economist [Oskar Morgenstern](https://www.britannica.com/money/Oskar-Morgenstern) in their 1944 book The Theory of Games and Economic Behavior. In game theory, a zero-sum game is one, such as chess or checkers, where each player has a clear purpose that is completely opposed to that of the opponent. In economics, a situation is zero-sum if the gains of one party are exactly balanced by the losses of another and no net gain or loss is created; however, such situations in real life are rare.