dirty word vs oath

dirty word

noun
  • A word that is considered vulgar, not necessarily sexual in nature. 

  • The name of a topic that a person does not like to hear or discuss. 

oath

noun
  • A curse, a curse word. 

  • A light, irreverent or insulting appeal to a deity or other entity. 

  • A solemn pledge or promise that invokes a deity, a ruler, or another entity (not necessarily present) to attest the truth of a statement or sincerity of one's desire to fulfill a contract or promise. 

  • A statement or promise which is strengthened (affirmed) by such a pledge. 

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