Mousiest means timid, meek or shy, but there are many antonyms for this word that describe people who are shameless, bold and confident. For instance, a few antonyms for mousiest include courageous, audacious, fearless, daring, and gutsy. People who possess these characteristics are known to be self-assured, assertive, and brave, and they are not afraid to take risks or speak their minds. They stand out in a crowd and command attention. So, when looking for antonyms for mousiest, look for words that describe people who are steadfast, resolute and fearless in their pursuits, and who radiate the strength and confidence that comes from knowing one's worth.