affine vs brother-in-law

affine

noun
  • A relative by marriage. 

verb
  • To refine. 

adj
  • Of or pertaining to a function expressible as f(⃑x)=A⃑x+⃑b (where A is a linear transformation and ⃑b is a constant), which, regarded as a transformation, maps parallel lines to parallel lines and finite points to finite points. 

  • Assigning finite values to finite quantities. 

  • Of two materials, having mutual affinity. 

brother-in-law

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

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

  • The brother of one's spouse. 

  • The husband of one's sibling. 

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