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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.
Examples of tachometer in a Sentence
Michael Harley, Forbes.com, 23 Apr. 2025
The engine rasps and rumbles right up to the tachometer’s 7,000-rpm redline—and beyond, in fact, since peak power arrives at 7,500 rpm.
—Michael Teo Van Runkle, Forbes.com, 23 Apr. 2025
The idea is to inform drivers when to shift the eight-speed transmission through pure audio feedback, without having to look at the tachometer.
—Karl Brauer, Forbes, 12 Mar. 2025
Gone are tangibles like the mechanically sweeping tachometer and the physical Engine Start button, replaced by a 15.6-inch instrument panel, a 10.25-inch central touchscreen, and an 8.8-inch screen along the passenger side of the dashboard.
—Basem Wasef, Robb Report, 25 Feb. 2025
See All Example Sentences for tachometer
Cite this Entry
“Tachometer.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/tachometer. Accessed 13 May. 2025.
Copy CitationKids Definition
tachometer
noun
from Greek tachos "speed" and English meter "an instrument for measuring"
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