From Proto-Germanic *kaf- (husk)—the discarded outer covering of grain, metaphor for all things worthless.
The dry, scaly protective casings of the seeds of cereal grain, separated during threshing.
From Old English 'ceaf,' from Proto-Germanic *kaf- (husk), possibly related to a root meaning 'to gnaw' or 'to chew.' The metaphor of separating wheat from chaff—keeping what is valuable and discarding the rest—appears in the Bible (Matthew 3:12) and has shaped English idiom ever since. Key roots: *kaf- (Proto-Germanic: "husk, outer