first cousin once removed vs step-uncle

first cousin once removed

noun

  • A parent's first cousin. 

  • A first cousin's child. 

step-uncle

noun

  • The brother of someone's stepmother or stepfather. 

  • The stepbrother of someone's mother or father. 

How often have the words first cousin once removed and step-uncle occurred in a corpus of books? (source: Google Ngram Viewer )