Concept:An antonym is a word opposite in meaning to the given word.Explanation:“Audacious” means bold, daring, or fearless.Its opposite should mean shy, fearful, or lacking courage.“Timid” means shy and easily frightened, so it is the correct antonym.“Vulgar” means crude, “Extinct” means no longer existing, and “Fickle” means changeable.Answer:Timid