Phys. and Path. [f. TONIC + -ITY. So mod.F. tonicité (Roquefort, 1829).] Tonic quality or condition; the property of possessing tone (see TONE sb. 7); the normal state of elastic tension of living muscles, arteries, etc., by which the tone of the organs is maintained.
1824. Bostock, Elem. Syst. Physiol., I. iii. 176. Besides contractility,… the muscular fibre has been supposed to possess another specific … quality, which has been called tone or tonicity.
1834. Good’s Study Med. (ed. 4), I. 242. Even the tonicity of the skin seems to be quite destroyed.
1851. Carpenter, Man. Phys. (ed. 2), 212. These same muscles exhibit a tendency to a moderate and permanent contraction, which is not shown by them when they are dead…; this endowment … is called Tonicity.
1899. Allbutt’s Syst. Med., VIII. 75. An apparently increased tonicity of the muscles.
b. Of spasm: see TONIC a. 1.
1897. Allbutt’s Syst. Med., II. 695. Tetanus … may be distinguished by the shorter incubation period, the tonicity of the spasms [etc.].
