The event of small airborne particles falling to the ground in significant quantities as a result of major industrial activity, volcano eruption, sandstorm, nuclear explosion, etc.

plural of fallout

material settling from a radioactive plume, and its subsequent surface deposition

A thick-walled building, usually under the ground, built so that people can keep away from dust after a nuclear explosion.

plural of radioactive fallout

plural of fallout shelter

(business) The dismissal of executives no longer required in their roles after a merger or acquisition.