guideword vs precept

guideword

noun
  • Any of the words in a memo or email that define metadata regarding the message, such as sender, recipient, and subject. 

  • A watchword; a word or phrase that serves as one's guide. 

  • A word that is printed at the top or bottom of the page in a reference work, in order to help readers find a specific entry. 

precept

noun
  • A written command, especially a demand for payment. 

  • An order issued by one local authority to another specifying the rate of tax to be charged on its behalf. 

  • A rule or principle, especially one governing personal conduct. 

  • A rate or tax set by a precept. 

verb
  • To act as a preceptor; to teach a physician-in-training by supervising their clinical practice. 

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