bathhouse vs hot tub

bathhouse

noun
  • A building with baths for communal use. 

  • A building where swimmers can change clothes. 

  • A business with bath-like facilities, which chiefly serves as a place for sexual encounters, especially among men. 

hot tub

noun
  • A large tub, often situated outdoors, filled with hot water and used for communal leisure bathing. 

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