fast
1 Americanadjective
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moving or able to move, operate, function, or take effect quickly; quick; swift; rapid: a fast pain reliever;
a fast horse;
a fast pain reliever;
a fast thinker.
- Antonyms:
- slow
-
done in comparatively little time; taking a comparatively short time: fast work.
a fast race;
fast work.
- Antonyms:
- slow
-
(of time)
-
indicating a time in advance of the correct time, as of a clock.
-
noting or according to daylight-saving time.
-
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adapted to, allowing, productive of, or imparting rapid movement: one of the fastest pitchers in baseball.
a hull with fast lines;
one of the fastest pitchers in baseball.
-
characterized by unrestrained conduct or lack of moral conventions, especially in sexual relations; wanton; loose.
Some young people in that era were considered fast, if not downright promiscuous.
- Synonyms:
- prodigal, wild, immoral, profligate, dissolute, dissipated
- Antonyms:
- restrained
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characterized by hectic activity.
leading a fast life.
- Antonyms:
- restrained
-
resistant.
acid-fast.
-
firmly fixed in place; not easily moved; securely attached.
- Antonyms:
- loose
-
held or caught firmly, so as to be unable to escape or be extricated.
an animal fast in a trap.
- Synonyms:
- inextricable
-
firmly tied, as a knot.
-
closed and made secure, as a door, gate, or shutter.
-
such as to hold securely.
to lay fast hold on a thing.
-
firm in adherence; loyal; devoted.
fast friends.
-
permanent, lasting, or unchangeable: a hard and fast rule.
a fast color;
a hard and fast rule.
- Synonyms:
- enduring
-
Informal.
-
(of money, profits, etc.) made quickly or easily and sometimes deviously.
He earned some fast change helping the woman with her luggage.
-
cleverly quick and manipulative in making money.
a fast operator when it comes to closing a business deal.
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-
Photography.
-
(of a lens) able to transmit a relatively large amount of light in a relatively short time.
-
(of a film) requiring a relatively short exposure time to attain a given density.
-
-
Horse Racing.
-
(of a track condition) completely dry.
-
(of a track surface) very hard.
-
adverb
-
quickly, swiftly, or rapidly.
-
in quick succession.
Events followed fast upon one another to the crisis.
-
to hold fast.
- Synonyms:
- tenaciously, fixedly, securely
-
fast asleep.
-
in a wild or dissipated way.
- Synonyms:
- prodigally, wildly, recklessly
-
ahead of the correct or announced time.
-
Archaic. close; near.
fast by.
noun
idioms
-
pull a fast one, to play an unfair trick; practice deceit.
He tried to pull a fast one on us by switching the cards.
-
play fast and loose. play.
verb (used without object)
-
to abstain from all food.
-
to eat only sparingly or of certain kinds of food, especially as a religious observance.
verb (used with object)
noun
-
an abstinence from food, or a limiting of one's food, especially when voluntary and as a religious observance; fasting.
-
a day or period of fasting.
noun
adjective
-
acting or moving or capable of acting or moving quickly; swift
-
accomplished in or lasting a short time
fast work
a fast visit
-
(prenominal) adapted to or facilitating rapid movement
the fast lane of a motorway
-
requiring rapidity of action or movement
a fast sport
-
(of a clock, etc) indicating a time in advance of the correct time
-
given to an active dissipated life
-
of or characteristic of such activity
a fast life
-
not easily moved; firmly fixed; secure
-
firmly fastened, secured, or shut
-
steadfast; constant (esp in the phrase fast friends )
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sport (of a playing surface, running track, etc) conducive to rapid speed, as of a ball used on it or of competitors playing or racing on it
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that will not fade or change colour readily
a fast dye
-
-
proof against fading
the colour is fast to sunlight
-
( in combination )
washfast
-
-
photog
-
requiring a relatively short time of exposure to produce a given density
a fast film
-
permitting a short exposure time
a fast shutter
-
-
cricket (of a bowler) characteristically delivering the ball rapidly
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informal glib or unreliable; deceptive
a fast talker
-
archaic sound; deep
a fast sleep
-
informal a deceptive or unscrupulous trick (esp in the phrase pull a fast one )
-
a person who achieves results quickly, esp in seductions
adverb
-
quickly; rapidly
-
soundly; deeply
fast asleep
-
firmly; tightly
-
in quick succession
-
in advance of the correct time
my watch is running fast
-
in a reckless or dissipated way
-
archaic close or hard by; very near
-
informal to behave in an insincere or unreliable manner
interjection
verb
noun
Synonym Usage
See quick.
Other Word Forms
Derived Forms
Inflected Forms
Adjectives
Participles
Conjugated Forms
Present
-
fastsimple
-
fastssimple
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have fastedperfect
-
has fastedperfect
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am fastingprogressive
-
are fastingprogressive
-
is fastingprogressive
-
have been fastingperfect progressive
-
has been fastingperfect progressive
Past
-
fastedsimple
-
had fastedperfect
-
was fastingprogressive
-
were fastingprogressive
-
had been fastingperfect progressive
Future
Etymology
Origin of fast1
First recorded before 900; Middle English; Old English fæst “firm”; cognate with Dutch vast, Old Norse fastr “firm,” German fest; akin to fast 2
Origin of fast2
First recorded before 1000; Middle English fasten, festen, Old English fæstan; cognate with German fasten, Gothic fastan, Old Norse fasta
Origin of fast3
First recorded in 1670–80; alteration, by association with fast 1 ( def. ) (in the sense “firmly tied”), of late Middle English fest “fastening, mooring rope,” from Old Norse festr “mooring rope, cable,” from Old Norse fastr “fixed, firm”; cf. fasten, fast 1
Explanation
When you see fast, you might think of Olympic runner Usain "Lightning" Bolt or a Porsche 911 Turbo. Alternatively, and quite confusingly, fast also means to refrain from eating for a certain period, usually for religious reasons. Fast is another of those deceptively simple words that have a number of other meanings beyond their most common usages. If something "sticks fast" it means it cannot be removed — like a leech or a stain. "To stand fast" means not to give up your point of view or to remain loyal. Then there's also the slang meaning of living beyond the constraints of normal behavior — as in "the fast life," "the fast track," or "the fast lane."
Vocabulary lists containing fast
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
"We should be spending on capex as fast as we can spend... without it being too wasteful," Musk said.
From Barron's ● Jul. 22, 2026
Friar told company leaders she worried that the company might not be able to pay for future computing contracts if revenue doesn’t grow fast enough.
From The Wall Street Journal ● Jul. 22, 2026
Let’s be clear: The core PCE index also shows inflation rising — and rising too fast for the Fed’s taste.
From MarketWatch ● Jul. 22, 2026
“AI is fast at execution, but execution was never the hard part of the job,” she said.
From Los Angeles Times ● Jul. 22, 2026
“They’re fast and big. And I like the noise they make.”
From "Keeping Pace" by Laurie Morrison
That was a faster rise than the 5.9% average recorded since 2000, and was unusual in other respects.
From The Wall Street Journal ● Jul. 23, 2026
"The commercial market has grown faster than the clinical evidence base," the paper read, and "the absence of adequate clinical evidence for use in humans is an alarming safety concern."
From Barron's ● Jul. 23, 2026
Under normal conditions, volatility is often viewed as a fear gauge, as it tends to rise as prices fall, because stocks tend to fall faster than they rally.
From MarketWatch ● Jul. 22, 2026
This allows them to return faster than many competing plants and take over even more territory.
From Science Daily ● Jul. 22, 2026
Danny dressed even faster because getting to Pili was a sure way of never having to return somewhere like that again.
From "The Way to Rio Luna" by Zoraida Cordova
Tesla is embarking on a massive construction spree that Musk characterized on a conference call as probably the United States' "fastest industrial scale up since World War Two."
From Barron's ● Jul. 22, 2026
Kerr wasn’t the most obvious candidate—he wasn’t even the fastest active miler in the world at the time.
From The Wall Street Journal ● Jul. 22, 2026
Those categories where the price rises are fastest are in video/ audio, financial services, medical services and airfares/ transportation.
From MarketWatch ● Jul. 20, 2026
Hadjar is the second driver to receive a grid penalty for engine-related issues this weekend - world champion Lando Norris, who was seventh fastest, will also drop 10 places for using too many batteries.
From BBC ● Jul. 17, 2026
The first pupil with his hand in the air, the fastest player on the soccer field, but for all that, just another kid in Conor’s class.
From "A Monster Calls" by Patrick Ness
Bishnoi meditates every morning and fasts many days of the month, the cousin said.
From The Wall Street Journal ● Jul. 9, 2026
Other recent studies on prolonged fasting have also found that the body enters a deep ketogenic state during multi day fasts, dramatically changing how cells use fuel.
From Science Daily ● May 17, 2026
Bonta, who intermittently fasts and tries not to eat before noon, was sticking to black coffee.
From Los Angeles Times ● Feb. 19, 2025
Alcodray says he fasts from 6:20 a.m. until around 8 p.m.
From Seattle Times ● Mar. 16, 2024
He was a silent, brooding man, given to fasts and contemplation, going often, alone, into the caves of the mountains, in the section of Virginia where he lived.
From "Harriet Tubman: Conductor on the Underground Railroad" by Ann Petry
These individuals typically ate their first meal after 14:00 and fasted for about 17 hours.
From Science Daily ● Apr. 11, 2026
In came the resistance bands, dead lifts, dumbbells and agility drills, plus a private chef who got a sweet break from 8 p.m. until noon the next day, as Doncic intermittently fasted.
From The Wall Street Journal ● Sep. 16, 2025
He was joined by thousands who fasted with him and held demonstrations.
From BBC ● Oct. 23, 2024
The same year, 1988, she fasted in solidarity with her grandfather to protest the use of pesticides on table grapes, and passed out fliers about the issue to grocery store customers in Fresno.
From Los Angeles Times ● Aug. 18, 2024
She even slept and fasted in the woods for a name, but the spirits were stubborn.
From "The Birchbark House" by Louise Erdrich
At the protest site in the capital Delhi, he began fasting on 28 June and has consumed nothing but salt and water since then, losing more than 9kg.
From BBC ● Jul. 20, 2026
When Potti Sriramulu began fasting in October 1952, he was asking for something then prime minister Jawaharlal Nehru had repeatedly resisted: a separate state for Telugu speakers.
From BBC ● Jul. 16, 2026
"Hunger strikes are a global form of protest, not uniquely Indian," says Sayantan Saha Roy, an anthropologist at the University of Connecticut whose recent research explores the politics of fasting.
From BBC ● Jul. 16, 2026
Researchers found that intermittent fasting and continuous calorie restriction produced similar weight loss.
From Science Daily ● Jul. 8, 2026
Matt didn’t mind fasting, but he felt sorry for Fidelito.
From "The House of the Scorpion" by Nancy Farmer
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.