invulnerable vs wetproof

invulnerable

adj

  • Incapable of being injured; not vulnerable. 

  • Unanswerable; irrefutable. 

wetproof

adj

  • Waterproof. 

verb

  • To make waterproof. 

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