- a washing out of earth, gravel, etc., by water, as from an embankment or a roadway by heavy rain or by a flash flood.
- the hole, break, or erosion produced by such a washing out.
- Also wash-out. Aeronautics. a warp in an airfoil that gives a decrease in the angle of attack toward the tip.Compare washin.
- Informal. an utter failure.
- Informal. a person who has failed a course of training or study: air force washouts.