Rev

google

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early 20th century: abbreviation of revolution.

wiktionary

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Abbreviation of revolutions, rpm

Abbreviation of revolution

rev (plural revs)

etymonline

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rev (v.)

"cause (an engine) to run quickly," especially when not in gear, 1916, from earlier noun (1901), shortening of revolution, in reference to the internal combustion engine. Related: Revved; revving.