- incapable of being dissolved: insoluble salts.
- incapable of being solved or explained: an insoluble problem.
- incapable of being dissolved; incapable of forming a solution, esp in water
- incapable of being solved
1610s, from Late Latin insolubilitas, from Latin insolubilis (see insoluble).
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]
- Not soluble.
- Not capable of being fully dissolved. Fats and oils are insoluble in water.