birdcage vs pigeonhole

birdcage

noun
  • A cage to keep pet or zoological specimen birds in. 

  • A game of chance played with dice; chuck-a-luck. 

pigeonhole

noun
  • One of an array of compartments for housing pigeons. 

  • A category. 

  • 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. 

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

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

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