The word "tach" is a short form of "tachometer," which is a device that measures the rotation speed or rate of something, usually in a vehicle. It helps us know how fast or slow something is spinning or rotating. Full definition
The Stingray's 6.2 - liter lopes effortlessly at 70 mph in seventh gear, tach needle buoyed under 1600 rpm. (roadandtrack.com)
The display changes based on the drive mode selected: An info - rich screen appears when in touring; a large tachometer is shown for sport mode; a race - car - inspired layout with tach band and lap timers appears for track mode. (autoweek.com)
Rather, all nav, vehicle, and infotainment information is delivered by smaller screens surrounding the large analog tach in front of the driver. (automobilemag.com)