speed

American  

[speed] / spid /

noun

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)

sped, speeded, speeding

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)

sped, speeded, speeding

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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Related Words

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

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

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

Speed, tools, technical fluency — that kind of knowledge matters.

From MarketWatch • May 7, 2026

But being far back turned out to be the place to be as Six Speed blazed through the first half-mile in 46.44 seconds and six furlongs in 1:10.90.

From Los Angeles Times • May 2, 2026

Speed is a large part of the appeal.

From Salon • Apr. 23, 2026

Speed is also important to merchants that want to restock returns as quickly as possible.

From The Wall Street Journal • Apr. 21, 2026

Such I did with Speed, finding Prince some Half-Mile olT, in a Ditch.

From "The Astonishing Life of Octavian Nothing, Traitor to the Nation, Volume I: The Pox Party" by M.T. Anderson

Related Words

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