speed(spēd),USA pronunciationn., v.,sped or speed•ed, speed•ing. n.
rapidity in moving, going, traveling, proceeding, or performing; swiftness; celerity:the speed of light; the speed of sound.
relative rapidity in moving, going, etc.; rate of motion or progress:full speed ahead.
full, maximum, or optimum rate of motion:The car gets to speed in just nine seconds.
Automotivea transmission gear ratio.
PhotographyAlso 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.
PhotographyAlso called shutter speed. the length of time a shutter is opened to expose film.
the largest opening at which a lens can be used.
Drugs, Slang Terms[Slang.]a stimulating drug, as caffeine, ephedrine, or esp. methamphetamine or amphetamine.
Informal Termsa 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.
[Archaic.]success or prosperity.
at full or 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.
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.
to promote the success of (an affair, undertaking, etc.); further, forward, or expedite.
to direct (the steps, course, way, etc.) with speed.
to increase the rate of speed of (usually fol. by up):to speed up industrial production.
to bring to a particular speed, as a machine.
to cause to move, go, or proceed with speed.
to expedite the going of:to speed the parting guest.
[Archaic.]to cause to succeed or prosper.
to move, go, pass, or proceed with speed or rapidity.
to drive a vehicle at a rate that exceeds the legally established maximum:He was arrested for speeding.
to increase the rate of speed or progress (usually fol. by up).
to get on or fare in a specified or particular manner.
bef. 900; 1965–70 for def. 6; (noun, nominal) 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, verbal) Middle English speden to succeed, prosper, go with speed, Old English spēdan to succeed, prosper; cognate with Old Saxon spōdian, Old High German spuoten
1, 2.See corresponding entry in Unabridged fleetness, alacrity, dispatch, expedition; hurry. 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.
11.See corresponding entry in Unabridged advance, favor.
13.See corresponding entry in Unabridged accelerate.
18.See corresponding entry in Unabridged See rush1.
the act or quality of acting or moving fast; rapidity
the rate at which something moves, is done, or acts
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
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
a numerical expression of the sensitivity to light of a particular type of film, paper, or plate See alsoISO rating
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