Question

tachometer Even though one purpose of a tachometer is to help drivers keep their engine speeds down, some of us occasionally try to see how high we can make the needle go. tachometer*

Accepted Answer

A device used to measure speed of rotation. A tachometer is literally a “speed-measurer,” since the Greek root tach- means “speed.” This is clear in the names of the tachyon, a particle of matter that travels faster than the speed of light (if it actually exists, it's so fast that it's impossible to see with any instrument), and tachycardia, a medical condition in which the heart races uncontrollably. Since the speed that an auto tachometer measures is speed of rotation of the crankshaft, the numbers it reports are revolutions per minute, or rpm's

word	tachometer
definition	A device used to measure speed of rotation.
eg_sentence	Even though one purpose of a tachometer is to help drivers keep their engine speeds down, some of us occasionally try to see how high we can make the needle go.
explanation	A tachometer is literally a “speed-measurer,” since the Greek root tach- means “speed.” This is clear in the names of the tachyon, a particle of matter that travels faster than the speed of light (if it actually exists, it's so fast that it's impossible to see with any instrument), and tachycardia, a medical condition in which the heart races uncontrollably. Since the speed that an auto tachometer measures is speed of rotation of the crankshaft, the numbers it reports are revolutions per minute, or rpm's
IPA	tachometer*

Tachometer Speed Device Measure Rotation Purpose Drivers Engine