Chaff/tʃæf/ Definition 1 of 3Pro Tip 1/3Agricultural Origin Originally refers to leftover parts during grain harvest, not the edible kernels. Threshing machines help to break the grain free of the chaff. Pro Tip 2/3Metaphoric Use Used metaphorically to differentiate valuable things from worthless ones. After some discussion, they could separate the clever ideas from the chaff. Pro Tip 3/3Historical Context Understanding historic grain processing can clarify this term's figurative use. In history, winnowing was a common way to remove chaff from the grain.