moral fiber

moral fiber

Ethical courage. The term dates from the second half of the 1800s. It was applied to World War II pilots who snapped under the strain of combat and refused to fly, and were then accused of lack of moral fiber. Playwright Terrence Rattigan used it in Flare Path (1942): “And on my confidential report they’d put—grounded. Lack of moral fibre” (2:2).
See also: moral