proliferation

noun

1. 1.The process by which an organism produces others of its kind; breeding, propagation, procreation, reproduction.
2. 2.The act of increasing or rising; augmentation, amplification, enlargement, escalation, aggrandizement.
3. 3.The result of building up; buildup, accretion.
4. 4.The spread of biochemical, nuclear and other weapons of mass destruction to countries not originally involved in developing them.