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 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 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

A survey conducted by the analysts found that convenience and speed of service helped attract customers, while higher menu prices and personal financial pressures were the main headwinds.

From The Wall Street Journal ● Jul. 22, 2026

As odysseys go, it’s very much my speed.

From Los Angeles Times ● Jul. 22, 2026

This means that both the speed and transmission behavior of optical signals could be reconfigured across entire systems containing multiple resonators, rather than only within a single resonator.

From Science Daily ● Jul. 22, 2026

Strong winds and a tinder-dry landscape meant that the fire advanced at frightening speed, devouring large amounts of territory in very little time.

From Barron's ● Jul. 22, 2026

As fast as I possibly can, dodging a luggage steward, vaulting over suitcases, and picking up speed midair.

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

Bikes without pedal assist, or those that can reach speeds higher than 28 mph are considered electric motorcycles and require a driver’s license and DMV registration.

From Los Angeles Times ● Jul. 21, 2026

The Sun has differential rotation, meaning that different latitudes rotate at different speeds.

From Science Daily ● Jul. 21, 2026

Iran has adapted to U.S. defenses, firing missiles that travel at extremely high speeds and can maneuver as they streak toward the earth, The Wall Street Journal has previously reported.

From The Wall Street Journal ● Jul. 20, 2026

A white truck slowly approaches the scene, but after the bison charges the truck the driver speeds off.

From BBC ● Jul. 13, 2026

The music starts slow, then speeds up crazy fast.

From "The House That Lou Built" by Mae Respicio

As he sped to the scene, he saw that a large motor boat was rapidly sinking.

From Los Angeles Times ● Jul. 17, 2026

The Crusades, for example, sped development of international finance and spurred creation of double-entry bookkeeping.

From The Wall Street Journal ● Jun. 29, 2026

As the driver sped off in the direction of the suspect, the officer continued giving him instructions.

From BBC ● Jun. 25, 2026

Warmer global temperatures don’t seem to have sped up the spread or evolution of primates into new species.

From Science Daily ● Jun. 20, 2026

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

From "Meltdown" by Deirdre Langeland

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

He said the deal with the private businessmen had speeded up redevelopment and was a key part of ensuring the site is successful.

From BBC ● Mar. 20, 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

He jumped and grabbed it, and shutting his mind to the sound and sight of the water, he ran back and then speeded forward.

From "Bridge to Terabithia" by Katherine Paterson

Minutes later, an ambulance was seen speeding away.

From BBC ● Jul. 18, 2026

Business owners say they recognize that Pico Boulevard has a speeding problem and can be dangerous for pedestrians.

From Los Angeles Times ● Jul. 17, 2026

While it is barely known outside the tech industry, its share price has soared around seven-fold this year, and in June it briefly became the largest Japanese firm by market capitalisation after speeding past Toyota.

From Barron's ● Jul. 15, 2026

It’s a civil offense, not even as bad as a speeding ticket.

From Salon ● Jul. 13, 2026

There are no tall buildings around or sirens or loud music and voices—just the soothing sound of speeding cars in the distance.

From "Pride" by Ibi Zoboi

Related Words

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