in doubt . in doubt {adv. phr.} In the dark; having some question or uncertainty. When in doubt about any of the words you're using, consult a good dictionary. Categories: add yours doubt {adv. phr.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2024 To section: I Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Comment on this entry