harebrained . harebrained {adj.} Thoughtless; foolish. Most of the harebrained things Ed does may be attributable to his youth and lack of experience. Categories: add yours add yours {adj.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2025 To section: H Subscribe to: American Idioms► Also consider the parent subscriptions (3)Idioms feedEnglish languageHome page and general feed Post my comment Post my comment