bawd vs side piece

bawd

noun
  • A person who keeps a house of prostitution, or procures women for prostitution; a procurer, a madame. 

  • A lewd person. 

side piece

noun
  • A mistress; a woman with whom a man carries on a physical affair (not emotional affair) without having the intention of forming a serious relationship. 

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