1. (used of solutions) having the same or equal osmotic pressure
   "The isotonic solutions prevented cell damage during the experiment";
   - isosmotic
    
2. (physiology) of or involving muscular contraction in which tension is constant while length changes
   "Lifting weights is an example of isotonic exercise"
    
3. (physiology) of two or more muscles; having equal tension
   "The isotonic contraction of the biceps and triceps muscles helps maintain balance in the arm"
    
4. Relating to or characterized by the equal intervals of a musical scale
   "isotonic tuning"

See also: tense

Antonym: isometric

Encyclopedia: Isotonic