insolubility (n.)

14世纪晚期，“不可摧毁的，无法松动的”，也比喻地用于问题等，“无法解决或解释的”，源自古法语 insoluble 或直接源自拉丁语 insolubilis “无法松动的”，来自 in- “不”（见 in-（1））和 solubilis “可松动的”（见 soluble）。

It was a tacit conviction of the learned during the Middle Ages that no such thing as an insoluble question existed. There might be matters that presented serious difficulties, but if you could lay them before the right man -- some Arab in Spain, for instance, omniscient by reason of studies into the details of which it was better not to inquire -- he would give you a conclusive answer. The real trouble was only to find your man. [Gertrude Bell, "The Desert and the Sown," 1907]

中世纪学者们心照不宣地认为，不存在无法解决的问题。可能会有一些问题存在严重的困难，但如果你能把它们放在正确的人面前——例如西班牙的某个阿拉伯人，由于研究的细节而无所不知——他会给你一个决定性的答案。真正的麻烦只是找到你的人。[杰特鲁德·贝尔，“沙漠与耕种”，1907年]

意思是“无法在液体中溶解”的，始于1713年。