bombproof vs waterproof

bombproof

verb
  • To make resistant to bomb blasts. 

adj
  • Sufficiently strong to resist the effects of a blast from a bomb. 

noun
  • An air-raid shelter, a structure designed to give protection against air raids and bombs. 

waterproof

verb
  • To make waterproof or water-resistant. 

noun
  • A substance or preparation for rendering cloth, leather, etc., impervious to water. 

  • Cloth made waterproof, or any article made of such cloth, or of other waterproof material, as rubber; especially, an outer garment made of such material. 

adj
  • Incapable of failing; unassailable. 

  • Resistant to the effects of water. 

  • Made of or covered with material that doesn't allow water in. 

How often have the words bombproof and waterproof occurred in a corpus of books? (source: Google Ngram Viewer )