catalyst vs rein

catalyst

noun
  • A substance that increases the rate of a chemical reaction without being consumed in the process. 

  • A catalytic converter. 

  • An object that facilitates the casting of a spell (such as a magic wand). 

  • Something that encourages progress or change. 

  • An inciting incident that sets the successive conflict into motion. 

rein

noun
  • A strap or rope attached to a bridle or bit, used to control a horse, animal or young child. 

  • The inward impulses; the affections and passions, formerly supposed to be located in the area of the kidneys. 

  • An instrument or means of curbing, restraining, or governing. 

verb
  • To restrain; to control; to check. 

  • To obey directions given with the reins. 

  • To direct or stop a horse by using reins. 

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