收割之後剩下的東西
最字面的一層：穀子處理完以後，人不吃的那些部分。
noun · C1
The dry, papery covers that come off grain seeds when grain is prepared for food. Chaff is too light and too hard to eat, so it is blown or shaken away and the seed is kept.
穀殼;糠
核心畫面
Picture a basket of grain thrown up into the air. The heavy seed drops back down; the dry husks are so light that the wind simply takes them. Chaff is the half that blows away. Every other use keeps one of two things from that moment: the lightness of what floats off, or the judgement that it was not the part worth keeping.
可以想成一籃穀子被拋向空中。重的穀粒落回籃子，乾殼太輕，風一吹就走了。chaff 就是飛走的那一半。後面每一個用法，…更多收起
可以想成一籃穀子被拋向空中。重的穀粒落回籃子，乾殼太輕，風一吹就走了。chaff 就是飛走的那一半。後面每一個用法，都留著這一幕裡的一樣東西：不是那種「輕飄飄、一撒就散」的感覺，就是那句「這不是要留的部分」的判斷。From the word’s history
From Old English ceaf, related to Dutch kaf and German Kaff. The word has always named the husk itself; the other uses are pictures taken from it.
來自古英語 ċeaf，跟荷蘭文 kaf、德文 Kaff 同源。這個字從一開始就是「穀殼」本身，其餘的用法都是從這個畫面借出去的。
Wiktionary etymology supplied in packet (source_ref kaikki:3f6f69a190036ae4:868063155)
Two branches
輕到會飄走的東西
從那一幕裡抽出「輕」跟「被篩掉」這兩點，套到穀子以外的東西上。
noun · C2
Things of no use or value, thought of as what is left over once everything worth keeping has been taken out.
無用的東西;糟粕