The term that describes a substance that cannot be dissolved in solution is insoluble.

Here's a breakdown:

* Soluble: A substance that can dissolve in a solvent to form a solution.

* Insoluble: A substance that cannot dissolve in a solvent to form a solution.

For example, salt is soluble in water, meaning it dissolves to form a salt solution. Sand, on the other hand, is insoluble in water, meaning it does not dissolve and will settle at the bottom of the container.