observance vs praxis

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. 

praxis

noun
  • Custom or established practice. 

  • The synthesis of theory and practice, without presuming the primacy of either. 

  • The deliberate action of a rational being. 

  • An example or form of exercise, or a collection of such examples, for practice. 

  • The practical application of any branch of learning. 

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