tach

/tæk/
noun
  1. Short for tachometer; an instrument that measures the rotation speed of an engine or shaft.
    • The driver glanced at the tach to see if the engine was revving too high.
    • The mechanic used a tach to check the idle speed of the motorcycle.
    • When the tach showed 4,000 RPM, he shifted gears smoothly.
Synonyms
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