1. a homogeneous mixture of one or more substances dispersed molecularly in a sufficient quantity of dissolving medium (solvent). The solute may be gas, liquid, or solid; the solvent is usually liquid, but may be solid, as in a solid solution of copper in silver (sterling silver). In pharmacology, a liquid preparation containing one or several soluble chemical substances usually dissolved in water and not, for various reasons, falling into another category. 2. the process of dissolving. 3. a loosening or separation.