Mrs. Warren's profession vs prostitution

Mrs. Warren's profession

prostitution

noun
  • Engaging in sexual activity with another person in exchange for goods (not necessarily money) or services. 

  • Debasement for profit or impure motives. 

  • Engaging in sexual activity with another person for pay. 

How often have the words Mrs. Warren's profession and prostitution occurred in a corpus of books? (source: Google Ngram Viewer )