the act of commemorating.

a service, celebration, etc., in memory of some person or event.

a memorial.

(in many Christian churches) a special service or prayer for commemorating the lesser feast on days on which two feasts of unequal rank are celebrated.

noun

forgetting , neglect , negligence , unobservance

noun

celebration , ceremony , custom , memorial service , monumentalization , recognition , remembrance , tribute , observance , monument