fast

1 of 5

adjective

ˈfast 

1

a

: characterized by quick motion, operation, or effect:

(1)

: moving or able to move rapidly : swift

a fast horse

(2)

: taking a comparatively short time

a fast race

(3)

: imparting quickness of motion

a fast bowler

(4)

: accomplished quickly

fast work

(5)

: agile of mind

especially : quick to learn

a class for fast students

b

: conducive to rapidity of play or action

a fast track

c(1)

of a timepiece : indicating in advance of what is correct

Your clock is two minutes fast.

(2)

: according to or being daylight saving time

d

: contributing to a shortening of exposure time

fast film

e

: acquired with unusually little effort and often by shady or dishonest methods

… had a keen eye for a fast buck …

—R. A. Keith

2

a

: firmly fixed

roots fast in the ground

b

: tightly shut

the drawers were fast

c

: adhering firmly

The boards were fast a few hours after being glued together.

d

: not easily freed : stuck

a ball fast in the mouth of the cannon

e

: stable

movable items were made fast to the deck

3

: firmly loyal

became fast friends

4

a

: securely attached

a rope fast to the wharf

b

: tenacious

a fast hold on her purse

5

a

archaic : sound asleep

b

of sleep : not easily disturbed

fell into a fast sleep

6

: not fading or changing color readily

fast colors

7

a

: actively seeking excitement and pleasure : wild

a pretty fast crowd

b

: sexually promiscuous

8

: resistant to change (as from destructive action or fading)

fast dyes

—often used in combination

sunfast

acid-fast bacteria

Usage of Safe

Both "drive safe" and "drive safely" are acceptable. Flat adverbs, as adverbs without -ly are called, are common in English; examples include soon in "see you soon" and fast in "time goes so fast." Adverbial safe functions in the same way these do.

fast

2 of 5

adverb

1

: in a firm or fixed manner

stuck fast

2

: in a sound manner : deeply

fast asleep

3

a

: in a rapid manner : quickly

b

: in quick succession

4

: in a reckless or dissipated manner

5

: ahead of a correct time or schedule

6

archaic : close, near

fast

3 of 5

verb

fasted; fasting; fasts

intransitive verb

1

: to abstain from food

2

: to eat sparingly or abstain from some foods

fast

4 of 5

noun (1)

1

: the practice of fasting

2

: a time of fasting

fast

5 of 5

noun (2)

: something that fastens (such as a mooring line) or holds a fastening

Synonyms of fast

Adjective

• rapid
• quick
• brisk
• galloping
• swift

Adverb

• quickly
• rapidly
• quick
• swiftly
• hot
• soon

Choose the Right Synonym for fast

fast, rapid, swift, fleet, quick, speedy, hasty, expeditious mean moving, proceeding, or acting with celerity.

fast and rapid are very close in meaning, but fast applies particularly to the thing that moves

fast horses

and rapid to the movement itself.

rapid current

swift suggests great rapidity coupled with ease of movement.

returned the ball with one swift stroke

fleet adds the implication of lightness and nimbleness.

fleet runners

quick suggests promptness and the taking of little time.

a quick wit

speedy implies quickness of successful accomplishment

speedy delivery of mail

and may also suggest unusual velocity.

hasty suggests hurry and precipitousness and often connotes carelessness.

a hasty inspection

expeditious suggests efficiency together with rapidity of accomplishment.

the expeditious handling of an order

Examples of fast in a Sentence

Adjective

She's a very fast runner.

We're off to a fast start.

We're now experiencing a faster rate of inflation.

We took the faster route.

Adverb

The boss expects this to be done this afternoon, so you'd better work fast.

He ran as fast as he could.

This is fast becoming a national problem.

You need to act fast to take advantage of this offer.

I don't know what caused the accident. It all happened so fast.

She's a woman who can think fast in a crisis.

He's going to have to talk fast to get himself out of this mess.

The window was stuck fast.

She held fast to her belief in justice.

We must stand fast and not surrender!

Verb

She always fasts on Yom Kippur.

Patients must fast for six hours before having the procedure.

Recent Examples on the Web

Adjective

Blashill wants the Blackhawks to be a fast-pressure team at both ends of the rink, one that attacks vertically but never cheats for offense. —Mark Lazerus, New York Times, 2 Nov. 2025

At each of two recent rallies, USA TODAY met pairs of volunteers who had met while canvassing and become fast friends. —Ben Adler, USA Today, 2 Nov. 2025

Adverb

Cozy Earth Soft Woven Long Sleeve Pajama Set Loungewear, bedding, and more are up to 50 percent off during Cozy Earth’s Last Chance Sale, but popular picks are selling out fast. —Maggie Horton, PEOPLE, 31 Oct. 2025

The Blue Jays got the scoring started early and fast after outfielder Davis Schneider took Dodgers starter Blake Snell deep in the first inning. —Jacob Lev, CNN Money, 30 Oct. 2025

Verb

Now that Halloween has passed, some people are ready to fast forward to December, put up Christmas lights, and embrace the winter holidays and festive spirit — just ask Mariah Carey. —Jalen Williams, Freep.com, 3 Nov. 2025

In mice, the scaly patches of irritated skin soon began growing new hair – and tests confirmed that white fat cells below the surface had shifted into fat-burning mode, revealing a burst of metabolic activity normally associated with fasting or cold exposure. —New Atlas, 29 Oct. 2025

Noun

For decades, venture capital chased the fast and the frictionless. —Nia Bowers, USA Today, 3 Nov. 2025

For example, some experts recommend consulting a healthcare professional to safely come off a fast instead of reverse dieting. —Emily Brown, Verywell Health, 23 Oct. 2025

Word History

Etymology

Adjective and Adverb

Middle English, from Old English fæst; akin to Old High German festi firm, Old Norse fastr, Armenian hast

Verb and Noun (1)

Middle English, from Old English fæstan

Noun (2)

alteration of Middle English fest, from Old Norse festr rope, mooring cable, from fastr firm

First Known Use

Adjective

before the 12th century, in the meaning defined at sense 2

Adverb

before the 12th century, in the meaning defined at sense 1

Verb

before the 12th century, in the meaning defined at sense 1

Noun (1)

12th century, in the meaning defined at sense 1

Noun (2)

15th century, in the meaning defined above

Phrases Containing fast

• acid-fast
• fast and furious
• fast and loose
• fast break
• fast casual
• fast day
• fast fashion
• fast-food
• fast-forward
• fast lane
• fast-pitch
• fast/quick buck
• fast/quick study
• fast-talk
• fast track
• fast-twitch
• going/getting nowhere fast
• going nowhere fast
• hard-and-fast
• not so fast
• play fast and loose
• pull a fast one
• thick and fast

Rhymes for fast

• bast
• blast
• cast
• caste
• classed
• clast
• gassed
• gast
• glassed
• grassed
• hast
• last

Kids Definition

fast

1 of 4 adjective

ˈfast 

1

a

: firmly fixed or bound

b

: tightly shut

c

: sticking firmly

2

: firmly loyal

became fast friends

3

a

: moving or able to move rapidly

b

: taking a short time

c

: giving quickness of motion (as to a thrown ball)

d

: favorable to speed

the faster route

4

: indicating ahead of the correct time

my clock is fast

5

: tricky and unfair

pulled a fast one

6

: not likely to fade

fast colors

fast

2 of 4 adverb

1

: in a fixed manner

stuck fast

2

: in a complete manner : soundly, deeply

fast asleep

3

: with great speed

a building fast going to ruin

fast

3 of 4 verb

1

: to go without eating

2

: to eat in small amounts or only certain foods

fast

4 of 4 noun

1

: the act of fasting

2

: a time of fasting

Etymology

Adjective

Old English fæst "firmly fixed"

Verb

Old English fæstan "to go without eating"

Medical Definition

fast

1 of 3 adjective

ˈfast 

1

: firmly fixed

2

a

: having a rapid effect

a fast medicine

b

: allowing for the rapid passage of a gas or liquid

3

: resistant to change (as from destructive action)

—used chiefly of organisms and in combination with the agent resisted

acid-fast bacteria

fast

2 of 3 intransitive verb

1

: to abstain from food

2

: to eat sparingly or abstain from some foods

transitive verb

: to deny food to

the patient is fasted and given a mild hypnotic

—Lancet

fast

3 of 3 noun

1

: the practice of fasting

2

: a time of fasting