flunk out flunk out {v. phr.} To have to withdraw from school or college because of too many failing grades. Fred flunked out of college during his junior year. Categories: add yours {v. phr.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2024 To section: F Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Leave my opinion