"Duly" is an adverb that indicates something is done or performed in accordance with what is required or expected. There are several synonyms for the word "duly," which include appropriately, correctly, rightfully, and properly. These words all suggest that something has been done in a manner that is considered fitting and in line with expectations. Other similar synonyms for "duly" include suitably, accurately, exactly, precisely, and correspondingly, among others. All of these synonyms convey a sense of obedience and compliance, indicating that something has been carried out in a manner that is consistent with the rules or norms.