isotonic

UK: /ˌaɪsəʊˈtɒnɪk/ US: (ī′sə ton′ik)

WordReference Random House Unabridged Dictionary of American English © 2025

i•so•ton•ic  (ī′sə ton′ik), adj. 

1. Chemistry Also, isosmotic. [Physical Chem.] noting or pertaining to solutions characterized by equal osmotic pressure. Cf. hypertonic (def. 2), hypotonic (def. 2).
2. Physiology
   • noting or pertaining to a solution containing the same salt concentration as mammalian blood.
   • noting or pertaining to a muscular contraction in which constant tension continues while the length of the muscle decreases, as during mechanical work.
3. Music and Dance of or characterized by equal tones.

• Greek isóton(os) having equal accent or tone (see iso-, tone) + -ic
• 1820–30;

i•so•to•nic•i•ty  (ī′sə tə nis′i tē), n. 

Collins Concise English Dictionary © HarperCollins Publishers::

isotonic / ˌaɪsəʊˈtɒnɪk/ adjective

1. (of two or more muscles) having equal tension
2. (of a drink) designed to replace the fluid and salts lost from the body during strenuous exercise
3. Also: isosmotic (of two solutions) having the same osmotic pressure, commonly having physiological osmotic pressure
   Compare hypertonic, hypotonic

isotonicity / ˌaɪsəʊtəʊˈnɪsɪtɪ/ noun