proliferation

American  

[pruh-lif-uh-rey-shuhn] / prəˌlɪf əˈreɪ ʃən /

noun

1. the growth or production of cells by multiplication of parts.

2. a rapid and often excessive spread or increase.

   nuclear proliferation.

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proliferation British  

/ prəˌlɪfəˈreɪʃən /

noun

1. rapid growth or reproduction of new parts, cells, etc

2. rapid growth or increase in numbers

3. a great number

   done up in a proliferation of fancy frills

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Etymology

Origin of proliferation

First recorded in 1855–60; proliferate + -ion

Explanation

Proliferation is a rapid multiplication of parts or the increase in the number of something. Nuclear proliferation is a rapid increase of nuclear weapons. The proliferation of any living thing will often create an overpopulation problem and cause an environmental imbalance. A proliferation of fuzzy koala bears might seem kind of nice, but these cute little creatures would soon eat up all the eucalyptus, running out of food and causing problems for other species. We almost always use this word to describe stuff we don't want to increase rapidly. The excessive proliferation of mutated cells, for instance, is how cancer grows.

Example Sentences

Proliferation of cards with big rewards—which come with bigger fees—have added to the expense.

From The Wall Street Journal • May 1, 2026

Darya Dolzikova, a senior Research Fellow with the UK-based RUSI's Proliferation and Nuclear Policy Programme, said the expiration of New Start was "concerning, because there are drivers on both sides to expand their strategic capabilities".

From BBC • Feb. 4, 2026

Per its international agreements, the United States has notified Russia and the more than 140 nations that are members of the Hague Code of Conduct Against Ballistic Missile Proliferation of the planned launch.

From Los Angeles Times • Feb. 18, 2025

He also helped create the Proliferation Security Initiative, an agreement to interdict shipments of materials for weapons of mass destruction.

From New York Times • Apr. 8, 2018

We will continue to create and strengthen international will to interdict material support, akin to our efforts in the Proliferation Security Initiative—a global effort to stop shipments of WMD, their delivery systems, and related material.

From National Strategy for Combating Terrorism September 2006 by National Security Council (U.S.)