moving or able to move, operate, function, or take effect quickly; quick; swift; rapid

a fast horse; a fast pain reliever; a fast thinker.

done in comparatively little time; taking a comparatively short time

a fast race; fast work.

(of time)

indicating a time in advance of the correct time, as of a clock.

noting or according to daylight-saving time.

adapted to, allowing, productive of, or imparting rapid movement

a hull with fast lines; one of the fastest pitchers in baseball.

characterized by unrestrained conduct or lack of moral conventions, esp. in sexual relations; wanton; loose

Some young people in that era were considered fast, if not downright promiscuous.

characterized by hectic activity

leading a fast life.

resistant

acid-fast.

firmly fixed in place; not easily moved; securely attached.

held or caught firmly, so as to be unable to escape or be extricated

an animal fast in a trap.

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 fast color; a hard and fast rule.

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.

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.

quickly, swiftly, or rapidly.

in quick succession

Events followed fast upon one another to the crisis.

tightly; firmly

to hold fast.

soundly

fast asleep.

in a wild or dissipated way.

ahead of the correct or announced time.

Archaic . close; near

fast by.

a fastening for a door, window, or the like. ?

play fast and loose. play ( def. 80 ) .

pull a fast one

Informal . to play an unfair trick; practice deceit

He tried to pull a fast one on us by switching the cards.

adjective

plodding , slow , tardy , unhurried , flexible , impermanent , insecure , loose , movable , unattached , unfixed , good , moral , upright

adverb

slow , slowly , loosely , unfixedly

noun

eating , feast , gluttony , gorging , stuffing

verb

eat , glut , gorge , stuff

adjective

accelerated , active , agile , blue streak , breakneck * , brisk , chop-chop * , dashing , double-time , electric , expeditious , expeditive , flashing , fleet , fleeting , flying , hairtrigger , hasty , hot , hurried , hypersonic , in a jiffy , in nothing flat , lickety split , like a bat out of hell , like all get out , like crazy , like mad , nimble , on the double * , pdq , posthaste , presto , pronto , quick , racing , rapid , ready , screamin’ , snap * , snappy * , speedball , supersonic , swift , velocious , winged , adherent , ardent , attached , close , constant , constrained , durable , faithful , fastened , firm , fortified , glued , held , impregnable , indelible , inextricable , lasting , loyal , permanent , resistant , resolute , secure , set , sound , stable , staunch , steadfast , stuck , sure , tenacious , tight , true , true blue , unwavering , wedged , bawdy , careless , debauched , depraved , devil-may-care * , dissipated , dissolute , easy , extravagant , flirtatious , frivolous , gadabout * , giddy , incontinent , indecent , intemperate , lascivious , lecherous , lewd , libertine , libidinous , licentious , light , loose , lustful , profligate , rakish , reckless , salacious , self-gratifying , self-indulgent , sportive , sporty , unchaste , wanton , wild , breakneck , speedy , brief , short , gay , unbridled , unconstrained , uncontrolled , ungoverned , uninhibited , unrestrained , whorish , colorfast , clinging , steady , strong , allegiant , liege , allegro , celeritous , immoral , immovable , invincible , invulnerable , meteoric , precipitate , precipitous , prompt , rigid

adverb

apace , chop-chop * , expeditiously , flat-out * , fleetly , full tilt , hastily , hurriedly , in a flash , in haste , in nothing flat , in short order , like a flash , like a shot , like greased lightning , like wildfire , posthaste , presto , promptly , pronto , quick , quickly , rapidly , soon , swift , swiftly , deeply , firm , firmly , hard , securely , solidly , soundly , steadfastly , tight , tightly

noun

abstinence , diet , fasting , xerophagy

verb

abstain , deny oneself , diet , famish , forbear , go hungry , not eat , refrain , starve , active , apace , brisk , easy , enduring , expeditious , faithful , firm , fleet , flying , hasty , held , hurried , immovable , in no time , loose , loyal , permanent , promiscuous , pronto , quick , rapid , reckless , secure , speedy , stable , stationary , steadfast , stuck , swift , true , unyielding