(1) A mutual incorporation of two or more substances, without chemical union, the physical characteristics of each of the components being retained. A mechanical mixture is a mixture of particles or masses distinguishable as such under the microscope or in other ways; a physical mixture is a more intimate mixture of molecules, as in the case of gases and many solutions. (2) In chemistry, a mingling together of two or more substances without the occurrence of a reaction by which they would lose their individual properties, i.e., without permanent gain or loss of electrons. (3) In pharmacy, a preparation, consisting of a liquid holding an insoluble medicinal substance in suspension by means of acacia, sugar, or some other viscid material. [L. mixtura or mistura]