speed

American  

[speed] / spid /

noun

• speeds
  plural

1. rapidity in moving, going, traveling, proceeding, or performing; swiftness; celerity: the speed of sound.

   the speed of light;

   the speed of sound.

   Synonyms:

   hurry, expedition, dispatch, alacrity, fleetness

   Antonyms:

   slowness

2. relative rapidity in moving, going, etc.; rate of motion or progress.

   full speed ahead.

   Synonyms:

   hurry, expedition, dispatch, alacrity, fleetness

3. full, maximum, or optimum rate of motion.

   The car gets to speed in just nine seconds.

4. Automotive. a transmission gear ratio.

5. Photography.

   1. Also called film speed.  the sensitivity of a film or paper to light, measured by an ASA or DIN index, which assigns low numbers to slow film and higher numbers to faster film.

   2. Also called shutter speed.  the length of time a shutter is opened to expose the film or digital sensor inside the camera to light.

   3. the largest opening at which a lens can be used.

6. Slang. a stimulating drug, as caffeine, ephedrine, or especially methamphetamine or amphetamine.

7. Informal. a person or thing that is compatible with or typical of one's ability, personality, desires, etc..

   My speed is writing postcards on the porch while everyone else is tearing around the tennis court.

8. Archaic. success or prosperity.

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verb (used with object)

• speeds,
  present (3rd person singular)
• sped,
  past participle,  past
• speeded,
  past participle,  past (especially British)
• speeding
  present participle

1. to promote the success of (an affair, undertaking, etc.); further, forward, or expedite.

   Synonyms:

   favor, facilitate, advance

2. to direct (the steps, course, way, etc.) with speed.

3. to increase the rate of speed of (usually followed byup ).

   to speed up industrial production.

   Synonyms:

   accelerate

4. to bring to a particular speed, as a machine.

5. to cause to move, go, or proceed with speed.

6. to expedite the going of.

   to speed the parting guest.

7. Archaic. to cause to succeed or prosper.

verb (used without object)

• speeds,
  present (3rd person singular)
• sped,
  past participle,  past
• speeded,
  past participle,  past (especially British)
• speeding
  present participle

1. to move, go, pass, or proceed with speed or rapidity.

2. to drive a vehicle at a rate that exceeds the legally established maximum.

   He was arrested for speeding.

3. to increase the rate of speed or progress (usually followed byup ).

4. to get on or fare in a specified or particular manner.

5. Archaic. to succeed or prosper.

idioms

1. at full / top speed,

   1. at the greatest speed possible.

      We drove down the highway at full speed.

   2. to the maximum of one's capabilities; with great rapidity.

      He worked at full speed.

2. up to speed,

   1. operating at full or optimum speed.

   2. functioning or producing at an expected, acceptable, or competitive level; up to par.

      a new firm not yet up to speed.

speed British  

/ spiːd /

noun

1. the act or quality of acting or moving fast; rapidity

2. the rate at which something moves, is done, or acts

3. physics a scalar measure of the rate of movement of a body expressed either as the distance travelled divided by the time taken ( average speed ) or the rate of change of position with respect to time at a particular point ( instantaneous speed ). It is measured in metres per second, miles per hour, etc

4. a rate of rotation, usually expressed in revolutions per unit time

5. 1. a gear ratio in a motor vehicle, bicycle, etc

   2. ( in combination )

      a three-speed gear

6. photog a numerical expression of the sensitivity to light of a particular type of film, paper, or plate See also ISO rating

7. photog a measure of the ability of a lens to pass light from an object to the image position, determined by the aperture and also the transmitting power of the lens. It increases as the f-number is decreased and vice versa

8. a slang word for amphetamine

9. archaic prosperity or success

10. quickly

11. 1. operating at an acceptable or competitive level

    2. in possession of all the relevant or necessary information

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verb

1. to move or go or cause to move or go quickly

2. (intr) to drive (a motor vehicle) at a high speed, esp above legal limits

3. (tr) to help further the success or completion of

4. slang (intr) to take or be under the influence of amphetamines

5. (intr) to operate or run at a high speed

6. archaic

   1. (intr) to prosper or succeed

   2. (tr) to wish success to

speed Scientific  

/ spēd /

1. The ratio of the distance traveled by an object (regardless of its direction) to the time required to travel that distance.

2. Compare velocity

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speed More Idioms  

More idioms and phrases containing speed

• full speed ahead
• up to par (speed)

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Synonym Usage

Speed, velocity, quickness, rapidity, celerity, haste refer to swift or energetic movement or operation. Speed (originally prosperity or success) may apply to human or nonhuman activity and emphasizes the rate in time at which something travels or operates: the speed of light, of a lens, of an automobile, of thought. Velocity, a more learned or technical term, is sometimes interchangeable with speed : the velocity of light; it is commonly used to refer to high rates of speed, linear or circular: velocity of a projectile. Quickness, a native word, and rapidity, a synonym of Latin origin, suggest speed of movement or operation on a small or subordinate scale; quickness applies more to people ( quickness of mind, of perception, of bodily movement ), rapidity more to things, often in a technical or mechanical context: the rapidity of moving parts; a lens of great rapidity. Celerity, a somewhat literary synonym of Latin origin, refers usually to human movement or operation and emphasizes expedition, dispatch, or economy in an activity: the celerity of his response. Haste refers to the energetic activity of human beings under stress; it often suggests lack of opportunity for care or thought: to marry in haste; a report prepared in haste. See rush ¹.

Other Word Forms

Derived Forms

• speeder
  noun
• speedfulness
  noun
• speedingness
  noun
• overspeed
  verb
• outspeed
  verb (used with object)
• multispeed
  adjective
• speedful
  adjective
• speedless
  adjective
• speedfully
  adverb
• speedingly
  adverb

Inflected Forms

Nouns

• speeds
  plural

Participles

• speeding
  present
• sped
  past
• speeded
  past

Conjugated Forms

Present

• speed
  simple
• speeds
  simple
• have sped
  perfect
• have speeded
  perfect
• has sped
  perfect
• has speeded
  perfect
• am speeding
  progressive
• are speeding
  progressive
• is speeding
  progressive
• have been speeding
  perfect progressive
• has been speeding
  perfect progressive

Past

• sped
  simple
• speeded
  simple
• had sped
  perfect
• had speeded
  perfect
• was speeding
  progressive
• were speeding
  progressive
• had been speeding
  perfect progressive

Future

• will speed
  simple
• will have sped
  perfect
• will have speeded
  perfect
• will be speeding
  progressive
• will have been speeding
  perfect progressive

Etymology

Origin of speed

First recorded before 900; 1965–70 speed for def. 6; (noun) Middle English spede “good luck, prosperity, rapidity,” Old English spēd; cognate with Dutch spoed, Old High German spōt; akin to Old English spōwan “to prosper, succeed”; (verb) Middle English speden “to succeed, prosper, go with speed,” Old English spēdan “to succeed, prosper”; cognate with Old Saxon spōdian, Old High German spuoten

Explanation

Speed most often describes acceleration or a high rate of motion. When something picks up too much speed, it can run off course, like a kid on a bike zooming uncontrollably down a steep hill. Speed can be a noun or verb. As a noun, it's an indicator of pace, as in the speed of a car. As a noun, it's also a drug that keeps you awake, very awake. As a verb, it means to “move along quickly,” like how you speed around on your bike. A fun fact: while speed refers to the distance traveled by an object during a specific amount of time, velocity describes that distance, but in a specified direction.

Example Sentences

See Examples For:

speed speeds sped speeded speeding

The wind could change the direction and speed of a fire, he added, while burning embers could be carried ahead of the main flames and set fire to new areas.

From BBC ● Aug. 20, 2026

Levanon said he can’t prove it yet, but he’s convinced it’s the lightening speed and adoption of artificial intelligence.

From MarketWatch ● Aug. 20, 2026

Three hours into the tour, investigators alleged Hernandez-Umana attempted to speed through swell during a U-turn and swamped the bow.

From The Wall Street Journal ● Aug. 20, 2026

Engineers tilted LRO so its cameras could point toward the crater as the spacecraft passed roughly 60 miles above the lunar surface at a speed of about 1 mile per second.

From Science Daily ● Aug. 20, 2026

The wind would be at their backs and he might be able to pick up speed.

From "Storm Runners" by Roland Smith

Santa Ana wind gusts were forecast to reach speeds of 60 to 80 miles per hour, with peak gusts of 90 miles per hour in the mountains.

From Los Angeles Times ● Aug. 20, 2026

In a market where computing power is in short supply, Cerebras’s latest artificial-intelligence hardware promises ultrafast inference speeds.

From MarketWatch ● Aug. 19, 2026

As a result, their strides were shorter, and their walking speeds were slower.

From Science Daily ● Aug. 16, 2026

Although reporting on incidents has grown, the feeling in the sport is that there are more fatalities now as speeds increase.

From BBC ● Aug. 15, 2026

I force myself to ignore it, blinking moisture from my eyes as I push my board to its highest speeds along an empty stretch of highway.

From "Warcross" by Marie Lu

According to the CHP, Maddalyn’s Acura was struck by a yellow Chevrolet Camaro and a black Dodge Charger that sped into the intersection.

From Los Angeles Times ● Aug. 19, 2026

Iryna Terekh, the young owner of a small furniture company, sped out of the town of Bucha with her ailing mother in the passenger seat.

From The Wall Street Journal ● Aug. 15, 2026

"They even have make-up artists to help you," she said as she mounted a crimson superbike, wrapped her arms around her driver and sped off with a videographer in pursuit.

From Barron's ● Aug. 2, 2026

Benefits costs have sped up compared to a year ago, while wage increases have slowed.

From MarketWatch ● Aug. 1, 2026

They sped for safety as the monster wave poured over the seawall behind them.

From "Meltdown" by Deirdre Langeland

Cooper said that while initial decisions on asylum applications had been speeded up, there had been "unacceptable delays" when people who were turned down decided to appeal.

From BBC ● Aug. 23, 2025

It wasn’t long before USC finally speeded away from Iowa, with Desmond Claude and Saint Thomas taking control to close out the Hawkeyes.

From Los Angeles Times ● Jan. 15, 2025

But the biggest thing Ghai and his family are doing does not directly involve workers at all: They’ve speeded up and expanded their use of technology, especially AI.

From Los Angeles Times ● May 1, 2024

She stressed it was an independent process and she was not involved directly but added: "I think everybody wants to see that speeded up."

From BBC ● Mar. 14, 2024

Immediately after the session ended, I speeded back with Duma Nokwe to find mother and daughter doing extremely well.

From "Long Walk to Freedom" by Nelson Mandela

Citi noted an “accelerating AI race” in China, as AI model developers are speeding up the release of ever more powerful models.

From The Wall Street Journal ● Aug. 20, 2026

Their frustration isn’t just rooted in annoyance at having surprise speeding tickets show up in the mail.

From Salon ● Aug. 14, 2026

The 48-year-old president drew criticism after Paris Match magazine splashed a photo of Macron speeding across the Riviera on a jet ski across its cover.

From Barron's ● Aug. 14, 2026

The court heard she already had nine points on her licence, from three speeding offences in June 2023 and then June and July 2025.

From BBC ● Aug. 3, 2026

But he’s already speeding toward the Park exit.

From "The Bletchley Riddle" by Ruta Sepetys and Steve Sheinkin

Related Words

• advance
• boost
• expedite
• facilitate
• fly
• further
• hasten
• help
• hurry
• promote
• quicken
• ride
• run
• rush
• zoom