A Quick and Simple Dictionary

containment

1. Noun.  the act of containing or something contained.
2. Noun.  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.
3. Noun.  a physical system designed to prevent the accidental release of radioactive or other dangerous materials from a nuclear reactor or industrial plant.
4. Noun.  (mathematics) an inclusion.