在液體裡散不開
這一支就是核心畫面本身：那杯怎麼攪都不會溶的水。
adjective · B2
An insoluble substance does not dissolve when you put it into a liquid. It stays as solid pieces instead of spreading through the liquid and disappearing.
不溶的；不溶解的
核心畫面
Picture stirring something into a glass of water. Sugar , spreads out and is gone; sand just sits there in grains, however long you stir. Insoluble is that second glass — whatever you do, it will not come apart. The same picture is what people reach for when a problem will not come apart either: you keep working at it, and it stays in one hard lump.
可以想成把東西攪進一杯水裡。糖會鬆開、散掉、不見了；沙子不管你攪多久，還是一粒一粒待在那裡。insoluble 就是…更多收起
可以想成把東西攪進一杯水裡。糖會鬆開、散掉、不見了；沙子不管你攪多久，還是一粒一粒待在那裡。insoluble 就是第二杯——怎麼弄都散不開。同一幅畫面也被拿來講問題：你一直想辦法，它還是硬硬地黏成一塊，拆不開。From the word’s history
From Latin insolubilis: in- plus solubilis, from a root meaning to loosen or undo. English kept both jobs of that root, which is why the same word covers a solid that will not loosen in water and a problem that will not come undone. The packet also records unsolvable and insolvable as words built from the same source.
來自拉丁文 insolūbilis：in-（不）加上 solūbilis，字根的意思是「鬆開、解開」。英文把這個字根的兩種工作都留了下來。所以同一個字既能講固體在水裡鬆不開，也能講問題解不開。同一個來源還長出了 unsolvable 和 insolvable。
Wiktionary etymology supplied in this packet (source_ref kaikki:3f6f69a190036ae4:1114415849): Latin insolubilis, in- + solubilis; piecewise doublet of insolvable and unsolvable
Two branches
問題解不開
把「鬆不開」從杯子搬到難題上：怎麼想都拆不開那個結。這是同一個字根的另一半工作，也是理解上的連結。
adjective · C1
An insoluble problem, conflict or question cannot be solved, or seems impossible to solve however hard people try.
無解的；解不開的