containment

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The act or condition of containing.
2. n. A policy of checking the expansion or influence of a hostile power or ideology, as by the creation of strategic alliances or support of client states in areas of conflict or unrest.
3. n. A structure or system designed to prevent the accidental release of radioactive materials from a reactor.

Century Dictionary and Cyclopedia

1. n. That which is contained or comprised; extent; contents.

Wiktionary

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

GNU Webster's 1913

1. n. obsolete That which is contained; the extent; the substance.
2. n. the act of containing.
3. n. (Diplomacy) the act or policy of restricting the influence or territorial growth of a hostile nation.
4. n. the act of restricting some deleterious substance within a confined space, especially when such material is released unintentionally or by accident. Also used attributively, as a containment boom.
5. n. a structure surrounding a nuclear power plant designed to prevent release of radioactive materials into the environment in the event of an accident.

WordNet 3.0

1. n. the act of containing; keeping something from spreading
2. n. (physics) a system designed to prevent the accidental release of radioactive material from a reactor
3. n. a policy of creating strategic alliances in order to check the expansion of a hostile power or ideology or to force it to negotiate peacefully