observance

(noun) the act of observing; taking a patient look. Synonyms: observation, watching.

(noun) a formal event performed on a special occasion. Synonyms: ceremony, ceremonial, ceremonial occasion. Example: "A ceremony commemorating pearl harbor."

(noun) the act of noticing or paying attention. Synonyms: notice, observation. Example: "He escaped the notice of the police."

(noun) conformity with law or custom or practice etc.. Synonyms: honoring.