bombproof

from WordNet (r) 3.0 (2006)

bombproof
    adj 1: able to resist the explosive force of bombs and shells;
           "bombproof shelter" [syn: {bombproof}, {shellproof}]
    n 1: a chamber (often underground) reinforced against bombing
         and provided with food and living facilities; used during
         air raids [syn: {bomb shelter}, {air-raid shelter},
         {bombproof}]
    v 1: make safe against bombings

from The Collaborative International Dictionary of English v.0.48

Bombproof \Bomb"proof`\, a.
   Secure against the explosive force of bombs. -- n. A
   structure which heavy shot and shell will not penetrate.
   [1913 Webster]