containment

Etymology

contain + -ment

noun

1. (uncountable) The state of being contained.
2. (uncountable, countable) The state of containing.
3. (obsolete, uncountable, countable) Something contained.
4. (uncountable, countable) A policy of checking the expansion of a hostile foreign power by creating alliances with other states; especially the foreign policy strategy of the United States in the early years of the Cold War.
   Mr. Putin has reinvigorated an alliance that spent years confused about its purpose once it lost the adversary it was formed to contain, the Soviet Union. Now, containment is back. 2022-02-18, David E. Sanger, “The United States’ Message to Russia: Prove Us Wrong”, in The New York Times, →ISSN
5. (countable) A physical system designed to prevent the accidental release of radioactive or other dangerous materials from a nuclear reactor or industrial plant.
6. (countable, mathematics) An inclusion.