Tonometer

n.	1.	(Physics.) An instrument for determining the rate of vibrations in tones.
	2.	(Physiol.) An apparatus for studying and registering the action of various fluids and drugs on the excised heart of lower animals.

Noun

1.

tonometer - measuring instrument for measuring tension or pressure (especially for measuring intraocular pressure in testing for glaucoma)

measuring device, measuring instrument, measuring system