pigeonhole vs retard

pigeonhole

verb
  • To put aside, to not act on (proposals, suggestions, advice). 

  • To categorize; especially to limit or be limited to a particular category, role, etc. 

noun
  • A category. 

  • One of an array of compartments for housing pigeons. 

  • One of an array of compartments for receiving mail and other messages at a college, office, etc. 

  • One of an array of compartments for storing scrolls at a library. 

  • A similar compartment in a desk, used for sorting and storing papers. 

retard

verb
  • To put off; to postpone. 

  • To decelerate; to slow down. 

  • To keep delaying; to continue to hinder; to prevent from progressing. 

noun
  • Retardation; delay. 

  • A slowing down of the tempo; a ritardando. 

  • A person or being who is extremely stupid or slow to learn. 

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