entombment vs requiem

entombment

noun
  • The decommissioning of a radioactive site by encasing it in concrete 

  • The act of entombing or the state of being entombed 

requiem

noun
  • A large or dangerous shark, specifically, (zoology) a member of the family Carcharhinidae. 

  • A piece of music composed to honor a dead person. 

  • A mass (especially Catholic) to honor and remember a dead person. 

  • A musical composition for such a mass. 

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