saw vs watchword

saw

verb
  • To make a motion back and forth similar to cutting something with a saw. 

  • To be cut with a saw. 

  • simple past tense of see 

  • To form or produce (something) by cutting with a saw. 

  • To cut (something) with a saw. 

noun
  • Such a tool with an abrasive coating instead of teeth. 

  • A sawtooth wave. 

  • A musical saw. 

  • A tool with a toothed blade used for cutting hard substances, in particular wood or metal. 

watchword

noun
  • A word used as a motto, as expressive of a principle, belief, or rule of action; a rallying cry. 

  • A prearranged reply to the challenge of a sentry or a guard; a password or signal by which friends can be known from enemies. 

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