A colloidal solution is a mixture of two substances, one of which is dispersed in the other. The dispersed substance is usually a solid, liquid, or gas, and the dispersion medium is usually a liquid or gas. In the crossword, the solution for the term COLLOIDAL SOLUTION is GEL, which is a type of colloidal solution. Gels are formed when particles of a solid are suspended in a liquid, forming a semi-solid material.