to make a mistake; fail to apply the materialslearned. Opposite of pass.to make a mistake; fail to apply the materialslearned. Cpposite of pass.failure on a course or examination or checkout. See also checkout in this glossary.make a mistake; fail to apply the materialslearned. Opposite of pass.make a mistake; fail to apply the materialslearned. Used in trainingdrills, the coach says "Flunk" when the student makes a mistake or incorrectly applies his materials. Flunk is the opposite of pass.indicate to a student that he has made a mistake or has failed to apply the materialslearned. In TRs, if the student does something other than what the drill calls for or omits doing something that is part of the drill, his twin says "Flunk," tells him what the error was and starts the drill over.