Airheaded refers to someone who is not intelligent, practical or serious in their thinking or behavior. The antonyms of airheaded are sensible, astute, intelligent, shrewd, prudent, smart, bright, sharp, clever, and insightful. A sensible person has a sober, practical outlook towards life and makes thoughtful, rational decisions. Someone who is astute has a keen perception, sharpness, and displays a remarkable ability to understand complex concepts. On the other hand, someone who is airheaded lacks these traits and may struggle to process information or take appropriate actions. Thus, it is important to choose one's words carefully to properly convey thoughts and accurately describe someone's qualities.