To*nom"e*ter (?), n. [Gr. a stretching, a tone + -meter.]
1. Physics.
An instrument for determining the rate of vibrations in tones.
2. Physiol. (a)
An apparatus for studying and registering the action of various fluids and drugs on the excised heart of lower animals.
(b)
An instrument for measuring tension, esp. that of the eyeball.
© Webster 1913.