decelerate
dee-SEL-uh-rayt
/diːˈsɛləreɪt/
To reduce speed or slow down a vehicle.
Emphasizes a controlled reduction in velocity rather than an abrupt emergency stop.
The story behind the word. Coined in 1899 as the direct antonym to accelerate, combining the prefix de- (down, away from) with Latin celer (swift). It gained rapid adoption as automotive braking systems required scientific measurement.
Word relationships
- slow down: Slow down is everyday conversational English, while decelerate is formal and precise.
- retard: Retard means delaying or slowing progress in a technical engineering context.
- accelerate: Accelerate means increasing speed.
Commonly confused with
- desecrate: Desecrate means treating something sacred with disrespect; completely unrelated!
Word family
- deceleration (noun): The reduction in speed or rate of slowing down.
Collocations
- decelerate gradually
- decelerate rapidly
- decelerate before turning
Idioms & expressions
- decelerate smoothly
Example sentences
- "As you approach the off-ramp, begin to decelerate gradually to exit safely." Approaching highway exit
- "Seeing the red light ahead, the driver allowed the vehicle to decelerate without slamming the brakes." Traffic signal control
Memory hook
DE-CELERATE = Decrease your celerity (speed). Decelerate = Slow down.
When not to use
Avoid using for sudden emergency locking of brakes unless describing the rate of speed reduction.
Fun facts
- Formula 1 drivers experience deceleration forces up to 5G when heavy braking at corners—five times their body weight!
Related words
Explore more words
Acceleration, accelerate, reduce, de-escalate, decouple, deteriorate
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