side piece vs woman

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. 

woman

noun
  • A wife (or sometimes a fiancée or girlfriend). 

  • All female humans collectively; womankind. 

  • A female person, usually an adult; a (generally adult) female sentient being, whether human, supernatural, elf, alien, etc. 

  • A female person who is extremely fond of or devoted to a specified type of thing. (Used as the last element of a compound.) 

  • A female attendant or servant. 

  • An adult female human. 

adj
  • Of or relating to a woman/women; female. 

verb
  • To furnish with, or unite to, a woman. 

  • To staff with female labor. 

  • To make effeminate or womanish. 

  • To call (a person) "woman" in a disrespectful fashion. 

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