observance

noun6

1. •
   The practice of complying with a law, custom, command or rule.
2. •
   The custom of celebrating a holiday or similar occasion.
3. •
   A rule governing a religious order, especially in the Roman Catholic church.

   • Thomas Merton was a monk in the Order of Cistertians of the Strict Observance.
4. •
   That which is to be observed.
5. •
   Observation or the act of watching.
6. •
   Reverence; homage.