tachometry

WordReference Random House Learner's Dictionary of American English © 2026

ta•chom•e•ter /tæˈkɑmɪtɚ, tə-/   n. [countable]

1. an instrument for indicating speed of rotation:
   The tachometer showed 2000 revolutions per second.

WordReference Random House Unabridged Dictionary of American English © 2026

ta•chom•e•ter  (ta kom′i tər, tə-), n. 

1. any of various instruments for measuring or indicating velocity or speed, as of a machine, a river, or the blood.
2. an instrument measuring revolutions per minute, as of an engine.

• 1800–10; tacho- + -meter

tach•o•met•ri•cal•ly  (tak′ə me′trik lē), adv.  ta•chom′e•try, n.