What is the meaning of Proliferation?

The process by which an organism produces others of its kind; breeding, propagation, procreation, reproduction.

The act of increasing or rising; augmentation, amplification, enlargement, escalation, aggrandizement.

The result of building up; buildup, accretion.

(Can we verify this sense?) The spread of biochemical, nuclear and other weapons of mass destruction to countries not originally involved in developing them.

Source: wiktionary.org