cousin vs son-in-law

cousin

noun
  • The child of a person's uncle or aunt; a first cousin. 

  • Something kindred or related to something else. 

  • Any relation who is not a direct ancestor or descendant but part of one's extended family; one more distantly related than an uncle, aunt, granduncle, grandaunt, nephew, niece, grandnephew, grandniece, etc. 

  • A member of the British intelligence services (from an American perspective) or of the American intelligence services (from a British perspective). 

son-in-law

noun
  • The husband of one's child. 

How often have the words cousin and son-in-law occurred in a corpus of books? (source: Google Ngram Viewer )