The word "most vociferant" means being very loud or outspoken. Some possible antonyms for "most vociferant" include quiet, reserved, subdued, low-key, restrained, muffled, soft-spoken, or hushed. If someone is not vociferant, then they might be calm, collected, composed, serene, tranquil, peaceful, placid, or mellow. Alternatively, if someone is too vociferant, they might be seen as aggressive, abrasive, obnoxious, rude, overbearing, confrontational, or argumentative. Therefore, it is important to find a balance between being assertive and being respectful, depending on the context and the audience. Different situations may call for different degrees of assertiveness or restraint, based on one's goals and values.