ta·​chom·​e·​ter ta-ˈkä-mə-tər How to pronounce tachometer (audio)
: a device for indicating speed of rotation

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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.

Example Sentences

Recent Examples on the Web Switching to M View adds a shift indicator and replaces the regular tachometer with one that's easier to read. Eric Stafford, Car and Driver, 25 Jan. 2023 One of the features is a choice of three display styles: the fully informative Classic, a Sporty version with a dynamic tachometer, and the minimalist Discreet setting. Jack Fitzgerald, Car and Driver, 18 Jan. 2023 The speedometer tops out at 360-kph (224 mph), with a 10,000 rpm tachometer redlining at 7800. Jack Fitzgerald, Car and Driver, 22 Dec. 2022 My speedo is broken, but the tachometer works fine. Kyle Hill, Discover Magazine, 29 Dec. 2013 While these screens have some user-experience issues and can be blocked by the steering wheel, the central tachometer still uses a physical needle that follows the engine's revs towards its heavenly 7400-rpm redline. Eric Stafford, Car and Driver, 17 Nov. 2022 Because of this, the car had to be equipped with a digital tachometer to display engine speed, since an analog version couldn’t keep up. Bryan Hood, Robb Report, 7 Oct. 2022 At 36mm, this chronograph with tachometer scale from around 1950 is among the largest Patek models of its era. Nick Scott, Robb Report, 7 May 2022 An analog speedometer and tachometer frame a small but easy-to-read 4.2-inch info display. Greg Fink, Car and Driver, 25 Apr. 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'tachometer.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History


Greek tachos speed + English -meter

First Known Use

1810, in the meaning defined above

Time Traveler
The first known use of tachometer was in 1810

Dictionary Entries Near tachometer

Cite this Entry

“Tachometer.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/tachometer. Accessed 26 Mar. 2023.

Kids Definition


ta·​chom·​e·​ter ta-ˈkäm-ət-ər How to pronounce tachometer (audio)
: a device for indicating speed of rotation

from Greek tachos "speed" and English meter "an instrument for measuring"

More from Merriam-Webster on tachometer

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