isotonic solution

A mixture containing the same concentration of solute as another mixture to which it is compared. When separated by a permeable membrane, osmosis does not occur. See also solution, hypertonic; solution, hypotonic and osmosis.

A solution that has no effect on the volume of tissues and cells. Thus, a cell, when placed in an isotonic solution tends neither to gain or lose water. Isotonic sports drinks have the same concentration as the body fluids.