white feather
noun
- a white feather given to someone as a sign that the giver considers them a coward（送给懦夫以示其懦弱的）白色羽毛。
短语
show the white feather
- Brit. dated behave in a cowardly fashion〈英, 旧〉显示懦弱, 显示胆怯。
词源
late 18th cent.: with reference to a white feather in the tail of a game bird， being a mark of bad breeding.