1) Acromyotonia 1) Tone 2) Tonicity 3) Tonus 
Myotonia (Myo from Greek; muscle, and Tonus from Latin; tension) is a symptom of a small handful of certain neuromuscular disorders characterized by delayed relaxation (prolonged contraction) of the skeletal muscles after voluntary contraction or electrical stimulation. Myotonia is present in Myotonia congenita, Paramyotonia Congenita and myotonic...
muscular disorder characterized by difficulty in relaxing voluntary muscles after contraction. All the muscles or only a few may be affected. The ... [1 related articles]
Temporary muscle spasm.
Increased muscular irritability and contractility with decreased power of relaxation; toxic spasm of muscle. ... (12 Dec 1998) ... 
(mi″o-to´ne-ә) dystonia involving increased muscular irritability and contractility with decreased power of relaxation; see also physiological tetanus. adj., myoton´ic., adj. myotonia atrophica myotonic dystrophy. myotonia congenita a h...
Type: Term Pronunciation: mī′ō-tō′nē-ă Definitions: 1. Delayed relaxation of a muscle after a strong contraction, or prolonged contraction after mechanical stimulation (as by percussion) or brief electrical stimulation; due to abnormality of the muscle membrane, specifically the ion channels.
[n] - abnormally long muscular contractions
myotonia Persistent contraction of skeletal muscle after the cessation of voluntary effort or electrical or mechanical stimulation; (chiefly with distinguishing word) any of several disorders characterized by this.
noun abnormally long muscular contractions; slow relaxation of a muscle after a contraction
tonic muscle spasm or muscular rigidity.