castling vs coop

castling

noun
  • A miniature cast or mould. 

  • One that is cast. 

  • The act of constructing a defense structure in Japanese chess in which the king (玉) is positioned in a certain way so that it is protected by pawns (歩) and silver general(s) (銀) and/or gold general(s) (金) often with an additional knight (桂) and lance (香車). 

  • A move in which the king moves two squares towards a rook, and the rook moves to the other side of the king; the action of the verb to castle. 

coop

noun
  • A small heap. 

  • A wickerwork basket (kipe) or other enclosure for catching fish. 

  • A cart with sides and ends made from boards, enabling it to carry manure, etc. 

  • A narrow place of confinement, a cage; a jail, a prison. 

  • A cart which opens at the back to release its load; a tumbril. 

  • A basket, pen or enclosure for birds or small animals. 

verb
  • To keep in a coop. 

  • To shut up or confine in a narrow space; to cramp. 

  • Of a police officer: to sleep or relax while on duty. 

  • To unlawfully confine one or more voters to prevent them from casting their ballots in an election. 

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