sibling vs similarity

sibling

noun
  • A person who shares a parent; one's brother or sister who one shares a parent with. 

  • A node in a data structure that shares its parent with another node. 

  • The most closely related species, or one of several most closely related species when none can be determined to be more closely related. 

similarity

noun
  • The relation of sharing properties. 

  • A transformation that preserves angles and the ratios of distances 

  • The property of two matrices being similar. 

  • Closeness of appearance to something else. 

How often have the words sibling and similarity occurred in a corpus of books? (source: Google Ngram Viewer )