Definition of "tachometer" [ta•chom•e•ter]

• An instrument used to measure the rotations per minute of a rotating shaft. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "To wit: The tachometer is the size of a wristwatch tucked into the left corner behind the steering wheel you can switch the display on the LCD screen, while the option for connecting to an iPhone takes prime and primary placement in the center console screen."
• "Now, there's a reason that, for about as long as we've had motorcars, a tachometer has been a round face with a needle: it works beautifully."
• "The tachometer is a logical choice, but I have a better idea: tap into pin #34 of the EEC-IV computer so the lights run off fuel flow calculations."