A substance that cannot dissolve.
A substance that cannot dissolve. Whether something is insoluble depends on the medium it is being mixed into, as well as the substance itself. So an oily compound might be insoluble in water, but dissolves easily in alcohol.
Whether something is insoluble depends on the medium it is being mixed into, as well as the substance itself. For example, many oily compounds are insoluble in water, but dissolve easily in alcohol.