Definition
 noun 
 (1) The muscle in a steady partially contracted state caused by the successive flow of nerve impulses.
 (2) The amount of tension or resistance to movement in a muscle.
 Supplement
 Muscle tone or tonus helps in maintaining body posture. For instance, the muscles holding the jaw keep it in position by contracting continuously and only partially. When a person loses consciousness or sleeps, the muscle tone declines.
 Word origin: tonus » Greek tónos (tone)
 Synonyms:
See also: hypotonia, hypertonia.