‖ tonus Physiol. and Path.
(ˈtəʊnəs)
[L. tonus, a. Gr. τόνος tone.]
1. The condition or state of muscular tone; the proper elasticity of the organs; tonicity.
| 1876 tr. Wagner's Gen. Pathol. (ed. 6) 162 In a reflex manner the arterial tonus is reduced or increased. 1882 J. S. Burdon-Sanderson in Lancet 29 Apr. 678 The paralysed artery recovers, and sometimes over-recovers its normal state of contraction, or, as we call it, its tonus. Tonus..is one of the independent endowments of arteries. 1899 Allbutt's Syst. Med. VII. 109 Whence comes this loss of tonus? |
2. A tonic spasm.
| 1891 in Cent. Dict. 1899 Allbutt's Syst. Med. VII. 890 The clonic spasm may..pass into slight tonus of very short duration. 1899 Syd. Soc. Lex., Tonus, tonic spasm. |
3. (See quot.)
| 1902 Encycl. Brit. XXXI. 740/1 A continuous lesser ‘change’ or stream of changes sets through the neuron, and is distributed by it to other neurons in the same direction and by the same synapses as are its nerve impulses. This gentle continuous activity of the neuron is called its tonus. |
4. Comb., as tonus-producing adj.
| 1897 Allbutt's Syst. Med. III. 317 Any failure of the circulation dependent upon the absence from the blood⁓stream of this tonus-producing substance. |