Deaccelerate

Part of speech: verb

Definitions

1. To slow down or decrease the velocity of something in motion
2. To reduce the speed or pace at which something is moving or progressing
3. To diminish the rate or momentum of movement or action

Etymology: "Deaccelerate" is a plain formation in English: the prefix "de-" added to "accelerate." The prefix comes from Latin "dē," meaning "down," "away," or "reversing," and it turns the verb into its opposite, so to deaccelerate is to slow down or lose speed. The base verb has a more physical history. "Accelerate" comes from Latin "accelerare," built from "ad-" ("to") and "celer" ("swift"), so the core sense is "to make swift." The Latin "celer" also gave English "celerity," meaning swiftness, and the same root sits behind words for quickness in many related languages. Because "deaccelerate" is a straightforward compound, its meaning is transparent: the reversal is built in, and no special story attaches to it beyond the history of its two parts.

Synonyms: decelerate, slow down, brake, retard

Antonyms: accelerate, speed up