The antonyms for the word "most ritual" are "least casual." While "most ritual" refers to something that is highly traditional or formal, "least casual" implies the opposite - something that is relaxed, informal, or spontaneous. Other antonyms for "most ritual" include "least ceremonial," "least conventional," or "least customary." These words can be used to describe events, activities, or behaviors that are informal, unconventional, or unstructured. For example, a casual gathering with friends at a local bar can be described as the antithesis of a formal dinner party with strict dress codes and traditional etiquette.