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¹fast

adjective \ˈfast\

: moving or able to move quickly

: happening quickly : taking a short amount of time

: operating quickly

Full Definition of FAST

a : firmly fixed <roots fast in the ground>

b : tightly shut <the drawers were fast>

c : adhering firmly

d : not easily freed : stuck <a ball fast in the mouth of the cannon>

e : stable <movable items were made fast to the deck>

: firmly loyal <became fast friends>

a : characterized by quick motion, operation, or effect: (1) : moving or able to move rapidly : swift (2) : taking a comparatively short time (3) : imparting quickness of motion <a fast bowler> (4) : accomplished quickly (5) : agile of mind; especially : quick to learn <a class for fast students>

b : conducive to rapidity of play or action

c (1) of a timepiece or weighing device : indicating in advance of what is correct (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>

a : securely attached <a rope fast to the wharf>

b : tenacious <a fast hold on her purse>

a archaic : sound asleep

b of sleep : not easily disturbed

: not fading or changing color readily

a : wild <a pretty fast crowd>

b : sexually promiscuous

: resistant to change (as from destructive action or fading) <fast dyes> —often used in combination <sunfast> <acid-fast bacteria>

See fast defined for English-language learners

See fast defined for kids

Origin of FAST

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

First Known Use: before 12th century

Related to FAST

Synonyms: blistering, breakneck, breathless, brisk, dizzy, fleet, fleet-footed, flying, galloping, hasty, hot, lightning, nippy, quick, rapid, rapid-fire, rattling, snappy, speedy, splitting, swift, whirlwind, zippy, at speed [chiefly British]

Antonyms: slow

Synonym Discussion of 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>.

Rhymes with FAST

bast, blast, cast, clast, gast, ghast, last, mast, Nast, past, vast

²fast

adverb

: with great speed : in a very short time : very quickly

: in a quick and intelligent way

: quickly and in a way that is meant to deceive or persuade someone

Full Definition of FAST

: in a firm or fixed manner <stuck fast>

: in a sound manner : deeply <fast asleep>

a : in a rapid manner : quickly

b : in quick succession

: in a reckless or dissipated manner

: ahead of a correct time or schedule

archaic : close, near

See fast defined for English-language learners

First Known Use of FAST

before 12th century

Related to FAST

Synonyms: apace, briskly, chop-chop, double-quick, fleetly, full tilt, hastily, hell-for-leather, hot, lickety-split, posthaste, presto, pronto, quick, quickly, rapidly, snappily, soon, speedily, swift, swiftly, a mile a minute, at full throttle, at full tilt, by leaps and bounds, in a hurry, in short order, like a shot, like gangbusters, like wildfire

Antonyms: slow, slowly

³fast

verb

: to eat no food for a period of time

Full Definition of FAST

intransitive verb

: to abstain from food

: to eat sparingly or abstain from some foods

See fast defined for English-language learners

Origin of FAST

Middle English, from Old English fæstan

First Known Use: before 12th century

⁴fast

noun

Definition of FAST

: the practice of fasting

: a time of fasting

First Known Use of FAST

before 12th century

⁵fast

noun

Definition of FAST

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

Origin of FAST

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

First Known Use: 15th century

FASTING Defined for Kids

¹fast

adjective \ˈfast\

fast·erfast·est

Definition of FAST for Kids

: moving, operating, or acting quickly <a fast train> <a fast thinker>

: taking a short time <a fast trip>

: indicating ahead of the correct time <The clock is fast.>

: firmly placed <The plant's roots were fast in the ground.>

: not likely to fade <fast colors>

: totally loyal <fast friends>

Synonym Discussion of FAST

fast, rapid, and swift mean moving, proceeding, or acting with great speed. fast is used of the thing that moves. <He rode a fast horse.> rapid is used of the speedy movement itself. <The horse moved at a rapid pace.> swift suggests ease of movement along with great speed. <A swift horse can easily jump the fence.>