atomic bomb vs thermonuclear weapon

atomic bomb

noun
  • A nuclear weapon that obtains its destructive energy from nuclear fission. 

  • The possession of one or more atomic bombs; the ability to launch a nuclear attack. 

thermonuclear weapon

noun
  • A weapon whose power is derived from nuclear fusion at high temperature 

How often have the words atomic bomb and thermonuclear weapon occurred in a corpus of books? (source: Google Ngram Viewer )