Antonyms for "airy-fairy" describe a concept or idea that is grounded in practicality, rationality, and realism. Words like practical, down-to-earth, level-headed, concrete, solid, substantive, and substantial convey the opposite of an airy-fairy notion. These antonyms emphasize the importance of tangible and measurable aspects of concepts, such as evidence, data, facts, and logic. Being grounded in reality, these antonyms highlight the necessity of being practical and sensible in decision-making, rather than relying on whimsical or magical thinking. Thus, using antonyms for "airy-fairy" represents a preference for realistic and evidence-based ideas.