brother-in-law vs stepmam

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. 

stepmam

noun

  • Stepmother. 

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