boetie vs brother-in-law

boetie

noun

  • brother 

  • man, fellow 

brother-in-law

noun

  • The brother of the spouse of one's sibling. 

  • The brother of one's spouse. 

  • The husband of the sibling of one's spouse. 

  • The husband of one's sibling. 

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