Synonyms for Fast:

adj.

abandoned (adjective)
unconstrained, ungoverned.
fast (adjective)
expeditious, speedy, rushing, hurrying, breakneck, swift, presto, light-footed, hasty, rapid, quick, snappy, galloping, allegro, dashing, fleet, nimble.
hasty (adjective)
abrupt, dashing, feverish, galloping, bustling, quick, breakneck, headlong, swift, brisk, rushing, impatient, breathless, hasty, flying, running, hurried, urgent, fleet, speedy, darting, rapid, pelting.
liege (adjective)
liege.
speeding (adjective)
racing.
speedy (adjective)
hasty, breakneck, in nothing flat, dashing, nimble, accelerated, hurried, electric, rapid, presto, hot, racing, pronto, quick, Posthaste, flying, brisk, active, expeditious, Lickety Split, fleet, fleeting, winged, like mad, like a bat out of hell, swift, snappy.
true (adjective)
truehearted.

adv.

quickly (adverb)
frenetic, headlong.
speedily (adverb)
promptly, like a flash, like wildfire, like a shot, like greased lightning, in a flash, quickly, apace, full tilt.

adv

quickly (adverb)
frenetic, in a flash/like a flash/quick as a flash, like mad.

n.

carnivore, washable, durable, brown-bag, crash diet, abstemious, indelible, Atkins diet, waterproof, cannibal, lasting, cannibalism, detox. dramatic, exotic, eventful, be careless, run wild, alive, exciting, thrilling, misbehave, compelling, exhilarating, deceive, enthralling. starve, forbear eating, deft, diet, observe a fast, at full speed/tilt/throttle, not eat, go hungry. darkroom, cartridge, developer, hell-for-leather, camera, boom, Asa, digicam, aperture, camcorder, celluloid. feeder, impassable, arterial, brief, short, two-way, passable, one-way. inactive, incontinent, rakish, uncontrolled, austere, abandoned, back-to-nature, restraint, licentious, unbridled, monastic, bohemian, wanton, new age, uninhibited, enclosed, wild, unconstrained, ungoverned, unrestrained, living, gracious. feminine, femininity, continue, female, womanhood, womanly, pert, matronly. taut, Clinging, tenacious, tense, tighten, free. stable, sure. constant, trust, liege, staunch, true, allegiant. flat out, like greased lightning, like a streak, in a flash, full tilt, like the wind, like a shot, pronto, like a blue streak, like a house on fire, like a flash, Posthaste, like a bat out of hell, apace, like wildfire, in nothing flat, quickly. abstention from eating (noun)
diet, fasting.
act (noun)
fasting.
fast (noun)
dissolute, immoral, flying, debauched, immobile, firm, quick, truehearted, allegretto, prestissimo, hot, fastened, fleet, express, speedy, immediate, instantaneous, locked, libertine, dyed, swift, high-velocity, double quick, faithful, winged, prompt, degenerate, tight, instant, smooth, speeding, loyal, secured, bolted, scurrying, allegro, blistering, tinted, accelerated, barred, riotous, accelerating, high-speed, vivace, latched, hurrying, degraded, dissipated, alacritous, presto, fixed, straightaway, andantino, fasting, red hot, colorfast, rapid, hastening, meteoric, profligate.
firmly fixed (noun)
firm, secure, immovable.
rapid (noun)
like a bat out of hell, swift, fleet, racing, quick, brisk, speedy, swift-footed, high-speed, fleeting.

v.

go without food (verb)
starve, not eat, go hungry.

Other synonyms:

female, inactive, abandoned, short. brief, tense, secure. constant. wild. true. easy. accelerated
accelerated.
double-quick
double quick.
nimble
swift-footed.
rapidly
quickly.

Usage examples for fast

  1. You do everything too fast – Roderick Hudson by Henry James
  2. I am going fast – The Secret Passage by Fergus Hume
  3. Hold on, Pudfut, don't walk so fast – The Veiled Lady and Other Men and Women by F. Hopkinson Smith