when hell freezes over when hell freezes over {adv. phr.}, {slang} Never. I'll believe you when hell freezes over. Contrast: UNTIL HELL FREEZES OVER. Categories: add yours add yours {adv. phr.} {slang} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2025 To section: W Subscribe to: American Idioms► Also consider the parent subscriptions (3)Idioms feedEnglish languageHome page and general feed Discuss Discuss