an underground living space designed to protect the occupants from the effects of a nuclear explosion.

Underground structures, stocked with food and other supplies, that were intended to keep people safe from radioactive fallout following a nuclear attack.

a shelter to protect occupants from the fallout from an atomic bomb

A pole-mounted structure used to replace prematurely fledged nestling martins by martin landlords who don't have accessible martin housing, or who don't keep written records. Parent martins will only feed young that are up off the ground, safe from ground-dwelling predators. The best place for such young, however, is back in their own nest.