observance in WordNet English dictionary

1. a formal event performed on a special occasion
   "a ceremony commemorating Pearl Harbor"
   ceremony  ceremonial  ceremonial occasion  observance 
   
2. conformity with law or custom or practice etc.
   honoring  observance 
   
3. the act of noticing or paying attention
   "he escaped the notice of the police"
   notice  observation  observance 
   
4. the act of observing; taking a patient look
   observation  observance  watching