[ speed ]
See synonyms for: speedspedspeeding on Thesaurus.com

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

  2. relative rapidity in moving, going, etc.; rate of motion or progress: full speed ahead.

  1. full, maximum, or optimum rate of motion: The car gets to speed in just nine seconds.

  2. Automotive. a transmission gear ratio.

  3. Photography.

    • 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.

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

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

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

  5. 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.

  6. Archaic. success or prosperity.

verb (used with object),sped [sped] /spɛd/ or speed·ed, speed·ing.
  1. to promote the success of (an affair, undertaking, etc.); further, forward, or expedite.

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

  1. to increase the rate of speed of (usually followed by up): to speed up industrial production.

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

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

  4. to expedite the going of: to speed the parting guest.

  5. Archaic. to cause to succeed or prosper.

verb (used without object),sped [sped] /spɛd/ or speed·ed, speed·ing.
  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.

  1. to increase the rate of speed or progress (usually followed by up).

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

  3. Archaic. to succeed or prosper.

Idioms about speed

  1. at full / top speed,

    • at the greatest speed possible: We drove down the highway at full speed.

    • to the maximum of one's capabilities; with great rapidity: He worked at full speed.

  2. up to speed,

    • operating at full or optimum speed.

    • functioning or producing at an expected, acceptable, or competitive level; up to par: a new firm not yet up to speed.

Origin of speed

First recorded before 900; 1965–70 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

synonym study For speed

1, 2. 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. 16. See rush1.

Other words for speed

Opposites for speed

Other words from speed

  • speedful, adjective
  • speed·ful·ly, adverb
  • speed·ful·ness, noun
  • speed·ing·ly, adverb
  • speed·ing·ness, noun
  • speedless, adjective
  • mul·ti·speed, adjective
  • outspeed, verb (used with object), out·sped or out·speed·ed, out·speed·ing.
  • o·ver·speed, verb, o·ver·sped or o·ver·speed·ed, o·ver·speed·ing.

Words Nearby speed

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use speed in a sentence

British Dictionary definitions for speed


/ (spiːd) /

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

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

  1. 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

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

    • a gear ratio in a motor vehicle, bicycle, etc

    • (in combination): a three-speed gear

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

  4. 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

  5. a slang word for amphetamine

  6. archaic prosperity or success

  7. at speed quickly

  8. up to speed

    • operating at an acceptable or competitive level

    • in possession of all the relevant or necessary information

verbspeeds, speeding, sped or speeded
  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

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

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

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

  4. archaic

    • (intr) to prosper or succeed

    • (tr) to wish success to

Origin of speed

Old English spēd (originally in the sense: success); related to spōwan to succeed, Latin spēs hope, Old Slavonic spěti to be lucky

Derived forms of speed

  • speeder, noun

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for speed


[ spēd ]

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

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Other Idioms and Phrases with speed


In addition to the idiom beginning with speed

  • speed up

also see:

  • full speed ahead
  • up to par (speed)

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.