castling vs reciprocity

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. 

reciprocity

noun
  • A reciprocal construction involves two noun phrases where each of the participants occupies both the role of agent and patient with respect to the other. see: Wikipedia:Reciprocal pronoun. 

  • A relation of mutual dependence or action or influence. 

  • A reciprocal relationship. 

  • The characteristic of being reciprocal, e.g. of a relationship between people. 

  • The mutual exchange of rights, privileges or obligations between nations. see: Wikipedia:Reciprocity (international relations). 

  • The responses of individuals to the actions of others. 

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