1. the quality or state of being silly, eccentric, or mentally unstable
Usage: informal

Examples

• The looniness of his plan became apparent when he suggested we travel to Mars by bicycle.
• Her friends loved her for her charming looniness and unpredictable sense of humor.
• The movie’s looniness made it a cult classic among comedy fans.
• Despite the apparent looniness of the idea, it actually worked quite well.
• The professor’s looniness was legendary among students who took his creative writing class.
• There’s a fine line between genius and looniness, and he walked it every day.