The antonyms for the word "most unexcessive" are "most excessive" or "most extravagant." These words describe excessive or extravagant behavior, actions or things. People who are most excessive go beyond the limits and do not bother about anything else. They might spend too much money or consume too much food, alcohol or drugs. On the other hand, people who are most unexcessive, are modest, simple and prefer to live within their means. They are not interested in splurging, wasting resources or harming others in any way. Therefore, it is important to understand the meaning of words and their antonyms to express ourselves better in conversations, writing or professional communication.