hypotonic /hī′pōton″ik/ [Gk, hypo, under, tonos, stretching] , 1. adj., pertaining to a lower or lessened tone or tension in any body structure, as in paralysis. 2. n., a solution having a lower concentration of solute than another solution, hence exerting less osmotic pressure than that solution. 3. adj., pertaining to a solution that causes cells to swell. Compare hypertonic, isotonic.
