speed
/spiːd/ (bre, ipa) · /spiːd/ (ame, ipa) · /ˈspēd/ (ame, mw)
speed — noun
- speedsingular
- speedsplural
1. a measure of how far something travels in a fixed amount of time, usually given
a measure of how far something travels in a fixed amount of time, usually given in units such as kilometres per hour or metres per second.
The train was moving at a speed of 220 kilometres per hour as it passed through the countryside.
at a speed of [number] + distance unit
Strong winds can reduce the speed of a cyclist by nearly half on a flat road.
speed of [something]
Nikos checked his cycling computer to see the average speed for the morning ride.
At full speed the ferry crosses the channel in just under two hours.
文法句型
at a speed of [number]
at high/low/full speed
speed of [something]
用法筆記
Speed differs from velocity because velocity also tells you the direction of movement. In everyday English, speed is far more common than velocity.
常見錯誤
2. the characteristic of acting or moving swiftly, without taking a long time.
the characteristic of acting or moving swiftly, without taking a long time.
Abigail was surprised by the speed with which the waiter brought their meals to the table.
the speed with which [clause]
The cheetah's speed makes it the fastest land animal on the planet.
Bilal completed the escape room with remarkable speed, finishing in under twelve minutes.
Lakan reacted with surprising speed and caught the glass before it hit the floor.
文法句型
with speed
at speed
用法筆記
This sense describes the quality of being fast rather than a measured rate. Compare with noun sense 1: 'the speed of the car was 80 km/h' (measured) vs 'he drove with great speed' (quality of fastness).
常見錯誤
3. a measurement that tells you how quickly a task or process is completed.
a measurement that tells you how quickly a task or process is completed.
The speed of the economic recovery surprised most financial analysts last year.
speed of [process]
Owen improved the typing speed of his students by running daily timed exercises.
Maja could not believe the speed at which the forest fire spread through the dry brush.
New software has doubled the processing speed of the company's payroll system.
文法句型
at speed
speed of [action/process]
用法筆記
Like sense 1, this can be measured, but it applies to how quickly a process completes rather than how far something travels. Common in business and technology contexts: 'processing speed', 'download speed', 'speed of service'.
4. the constant rate at which a wave, for instance a light wave or a sound wave, pa
the constant rate at which a wave, for instance a light wave or a sound wave, passes through a medium.
The speed of light in a vacuum is about 300,000 kilometres per second.
speed of light / sound (fixed scientific constant)
Sound travels at different speeds through water than it does through air.
Hiro explained that the speed of a wave depends on the material it passes through.
Measuring the speed of seismic waves helps geologists locate the centre of an earthquake.
文法句型
speed of light / sound / wave
用法筆記
In physics, this sense is almost always preceded by a prepositional phrase naming the wave type: 'the speed of light', 'the speed of sound'. These are well-known constant values used in calculations.
常見錯誤
5. a particular gear in a vehicle or bicycle that allows the wheels to turn at a di
a particular gear in a vehicle or bicycle that allows the wheels to turn at a different rate compared to the engine or pedals.
Kabir shifted into a lower speed before the bicycle began to climb the steep hill.
shift into / change speed
Antonia bought a twenty-one-speed mountain bike for riding on rough forest trails.
[number]-speed [bicycle / vehicle]
The old car struggled in fourth speed on the motorway, unable to maintain momentum.
Hiro's racing bike has eighteen speeds, which let him tackle both steep climbs and flat sprints.
- gear
more common in modern car contexts; 'speed' is more traditional for bicycles
文法句型
[number]-speed [vehicle]
first/second/third… speed
change speed
用法筆記
Common in compound nouns: 'three-speed bicycle', 'five-speed gearbox'. When counting gears, 'speeds' is the plural form. In modern cars, 'gear' is more common than 'speed' for this sense.
6. a number printed on photographic film that tells you how strongly the film react
a number printed on photographic film that tells you how strongly the film reacts to light; a higher number means the film needs less light to create a picture.
Tamar chose a film with a speed of 400 for the indoor birthday party with dim lighting.
film speed of [number] (ISO/ASA rating)
High-speed film allows photographers to take clear pictures in low light without a flash.
high-speed / low-speed film
Nia switched to a slower film speed because the afternoon sunlight was bright enough.
文法句型
film speed of [number]
high-speed film
用法筆記
Expressed as an ISO number (e.g., ISO 200, ISO 400). Higher numbers = more sensitive = faster speed. This sense is primarily used for traditional film cameras, not digital, though 'ISO speed' is still used in digital photography.
7. the period during which a camera's shutter remains open so that light can hit th
the period during which a camera's shutter remains open so that light can hit the film or digital sensor inside the camera body.
A fast shutter speed of 1/1000 second can freeze the motion of a bird in flight.
shutter speed of [time fraction]
With a slow shutter speed, Anjali captured the blur of car lights on the highway.
fast / slow shutter speed
The photographer adjusted both the aperture and the shutter speed to get the correct exposure.
文法句型
shutter speed of [fraction]
fast/slow shutter speed
用法筆記
Usually appears as 'shutter speed' rather than just 'speed' alone. Measured in fractions of a second (1/125, 1/250) or in whole seconds for long exposures.
8. an illegal drug, especially amphetamine or methamphetamine, that makes the user
an illegal drug, especially amphetamine or methamphetamine, that makes the user feel more awake and energetic.
The documentary warned young people about the dangers of using speed and other street drugs.
Police found a small quantity of speed hidden in the glove compartment of the stolen car.
collocation: quantity of speed / using speed
Recovery programmes help users break their addiction to speed and crystal meth.
- amphetamine
the medical name for the drug; neutral register
- meth
short for methamphetamine; also informal but more specific
- crystal
slang for crystal meth, a more potent form
用法筆記
Highly informal slang. Not used in formal or academic writing. The word appears without an article: 'He was arrested for selling speed', not 'a speed'. Use with caution in learner contexts.
常見錯誤
speed — verb
- speedpresent simple I / you / we / they
- speeds3rd person singular
- speeding-ing form
- spedpast simple
1. to move or cause something to move or happen more quickly than usual, often with
to move or cause something to move or happen more quickly than usual, often with a sense of urgency.
Nikos sped down the motorway to reach the airport before the check-in counter closed.
sped + adverb/preposition (intransitive)
The new manager speeded up the approval process for small project budgets.
speeded up [process] / speed [something] up (transitive)
An ambulance sped through the busy streets with its siren wailing.
Tamar sped past the other runners in the final lap and crossed the finish line first.
- hasten
more formal; often used for causing something to happen sooner
- accelerate
neutral; can be used for vehicles, processes, or growth
- rush
more informal; suggests hurry or lack of care
- decelerate
formal technical term
文法句型
speed + adverb/preposition
speed [something] up
speed along / through / past
用法筆記
The past form is usually 'sped', but 'speeded' is accepted, especially in the phrasal verb 'speed up' ('speeded up' is more common than 'sped up' in British English).
常見錯誤
2. to drive a vehicle faster than the legal limit allows on a particular road or ar
to drive a vehicle faster than the legal limit allows on a particular road or area.
Owen was fined three hundred dollars after a camera caught him speeding on the highway.
caught speeding (passive construction)
Nia admitted she had been speeding to get her daughter to the hospital on time.
A police officer pulled Bilal over and told him he was speeding in a school zone.
Kabir checked his rear-view mirror nervously, worried that he might be speeding.
文法句型
be speeding
get caught speeding
用法筆記
Almost always used in continuous tenses ('he was speeding', 'I am speeding'). The simple past 'sped' is uncommon for this sense; instead say 'he was caught speeding' or 'he drove too fast'. 'Speeding' as a gerund is also common: 'Speeding is dangerous.'