Definitionen
1.AdjectiveHaving the same osmotic pressure.
2.AdjectiveHaving the same concentration of solutes as human blood."Use an isotonic saline solution in your neti pot to prevent irritation of your nasal passages."
3.AdjectiveHaving equal tension.
4.AdjectiveOf or involving muscular contraction against resistance in which the length of the muscle changes. Antonym is isometric. Isotonic movements are either concentric (working muscle shortens) or eccentric (working muscle lengthens). See also Wikipedia:Isotonic (exercise physiology)
5.AdjectiveHaving the same tone.