'tachometer' originates from Modern English, specifically formed from Greek elements: the prefix 'tachy-' (from Greek 'takhós') meaning 'speed' and the suffix '-meter' (from Greek 'metron') meaning 'measure'.

'tachometer' was coined in the 19th century by combining 'tachy-' and '-meter' (via scientific/technical coinages in New Latin and Modern English), and it entered English usage to name devices that measure speed (especially rotational speed).

Initially coined to denote a device for measuring speed, its usage has specialized to mean an instrument that measures rotational speed (often given in RPM) rather than linear speed.