in game theory, designating or of a situation, competition, etc. in which a gain for one must result in an equal loss for another or others
See zero-sum in American Heritage Dictionary 4
adjective
Of or relating to a situation in which a gain is offset by an equal loss: “. . .under the zero-sum budgeting system that governs federal spending, the money for spinal research is likely to be deducted from some other research account”(Daniel S. Greenburg).