tonus

noun

1. (countable, uncountable)tonicity; tone

   “muscular tonus”

   “The amount of stretch possible increases with the range in the joint and decreases with the cross section of the muscle and the amount of tonus or contraction in these antagonists .”

   “Dr. H. S. Sullivan, for example, is known to many for his acute understanding of the postural tonuses of his patients.”

   “At the same time, from the vasomotor point of view the artrioles are an extremely active part of the vascular bed , and every important change in the peripheral resistance is traceable to a corresponding change in the tonus of the arterioles .”

2. (countable, uncountable)A tonal system or mode used in Gregorian chant.

   “Aurelian associates antiphons and toni of the plain chant, so that the octave-based Pythagorean scale is exemlified by means of the liturgical chant, with the outstanding consequence that church music becomes the sounding representation of the harmony of the spherese and of human beings.”