Definition - What does Insoluble mean?
Insoluble refers to the inability of one substance to dissolve in another. The substance that is dissolved is called a solute, while the other is referred to as a solvent.
Corrosionpedia explains Insoluble
Several substances that are insoluble, particularly in water, pose a risk to the environment. As such, strict regulations are in place to monitor their use and prevent pollution. Examples of some things that are insoluble are: plastic, metal, wax, oil, and gasoline.