lady vs side piece

lady

noun
  • The mistress of a household. 

  • A title for someone married to a lord or gentleman. 

  • A woman’s breast. 

  • A polite reference or form of address to women. 

  • A woman: an adult female human. 

  • A wife or girlfriend; a sweetheart. 

  • A title that can be used instead of the formal terms of marchioness, countess, viscountess, or baroness. 

  • A queen (the playing card). 

  • A woman of breeding or higher class, a woman of authority. 

  • A woman to whom the particular homage of a knight was paid; a woman to whom one is devoted or bound. 

  • The feminine of lord. 

  • Toilets intended for use by women. 

  • Used to address a female. 

  • Who is a woman. 

  • A five-pound note. (Rhyming slang, Lady Godiva for fiver.) 

  • A queen. 

verb
  • To address as “lady”. 

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 lady and side piece occurred in a corpus of books? (source: Google Ngram Viewer )