Observance is a term that pertains to the act of following or performing a traditional or religious ceremony or custom. However, there are plenty of synonyms that can be used interchangeably with this word to convey the same meaning, such as adherence, compliance, obedience, conformity, and adherence. These synonyms signify the action of adhering or conforming to a particular manner of thought or practice, as well as the duty to follow established customs or religious belief systems. Similarly, terms such as celebration, commemoration, festival, or ritual, can also be used to denote the act of commemorating a significant event or occasion with a particular set of practices or activities.