observance vs routine

observance

noun
  • The practice of complying with a law, custom, command or rule. 

  • That which is to be observed. 

  • Observation or the act of watching. 

  • A rule governing a religious order, especially in the Roman Catholic church. 

  • The custom of celebrating a holiday or similar occasion. 

  • Reverence; homage. 

routine

noun
  • A course of action to be followed regularly; a standard procedure. 

  • A set piece of an entertainer's act. 

  • A set of normal procedures, often performed mechanically. 

  • A set of instructions designed to perform a specific task; a subroutine. 

adj
  • Ordinary with nothing to distinguish it from all the others. 

  • According to established procedure. 

  • Regular; habitual. 

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