Definitions for "Nonproliferation"
Prevention of the spread of weapons of mass destruction.
the prevention of something increasing or spreading (especially the prevention of an increase in the number of countries possessing nuclear weapons); "they protested that the nonproliferation treaty was just a plot to maintain the hegemony of those who already had nuclear weapons"; "nuclear disarmament and nonproliferation are closely related goals"
The restriction of ability to easily access fissile materials in concentrations sufficient to assemble a nuclear weapon.