To make resistant to bomb blasts.
Sufficiently strong to resist the effects of a blast from a bomb.
An air-raid shelter, a structure designed to give protection against air raids and bombs.
to make resistant to failure.
To make proof against bullets.
Unbreakable, very tough.
Reliable, infallible, sturdy or error-tolerant.
Capable of withstanding a direct shot by a bullet fired from a gun.