Overspeed

Part of speech: verb, noun

Definitions

1. To exceed the designated or safe speed limit; to operate a machine or vehicle at a higher velocity than recommended; an instance or condition of moving faster than allowed
2. Moving beyond the prescribed speed boundary; causing equipment or transport to function at unsafe high speeds; a situation characterized by surpassing speed restrictions
3. Surpassing maximum authorized speed; driving or running machinery faster than safe operational limits; the state of exceeding established velocity thresholds

Etymology: "Overspeed" is about as plain as English compounds get: it joins the prefix "over-", meaning beyond or in excess of, to the noun "speed". The prefix is what carries the sense of going past a limit, so the word reads literally as going too fast. Its verb and noun uses both follow from that, whether the subject is a vehicle, a machine, or a person's pace. The word is a transparent formation, so the most useful thing to know is how the prefix works. "Over-" attached to a noun or verb regularly creates a word meaning excess, as in "overheat" or "overwork", and "overspeed" fits that pattern exactly. Its meaning is therefore assembled from parts a reader already knows, rather than drifting away from them.

Synonyms: exceed speed, overrun, race, speed up, accelerate

Antonyms: slow down, decelerate, under speed, brake, reduce speed