fast Definition

fast¹
adj faster, fastest

1. Moving, or able to move, quickly.

Thesaurus: rapid, swift, fleet, quick, speedy, accelerated, hasty, winged, like a bat out of hell (slang), like a house on fire (slang); Antonym: slow, sluggish.
2. Taking a relatively short time.
3. Said of a clock, etc: showing a time in advance of the correct time.
4. Allowing or intended for rapid movement.

Example: the fast lane
5. Said of a photographic film: requiring only brief exposure.
6. colloq
Tending to make sexual advances on rather brief acquaintance.
Thesaurus: promiscuous, loose, whorish, wanton, wild; licentious, profligate, immoral; Antonym: chaste.
7. Firmly fixed or caught; steadfast.

Thesaurus: firm, adherent, attached, stuck, immovable, secure, steadfast.
8. Said of friends: firm; close.
9. Said of fabric colours: not liable to run or fade.

Thesaurus: permanent, colour-fast, durable, lasting, washable, indelible, waterproof, vat-dyed.

adverb

1. Quickly; rapidly.

Thesaurus: rapidly, speedily, quickly, swiftly, hurriedly, hastily, apace, posthaste, lickety-split (slang), like a shot, like a flash, presto; Antonym: slow.
2. In quick succession.

Example: coming thick and fast
3. Firmly; tight

Example: The glue held fast.
Thesaurus: securely, firmly, tightly, fixedly; Antonym: loosely.
4. Deeply; thoroughly.

Example: fast asleep

Derivative: fastish
adj

Idiom: fast and furious

Fast and lively; frenzied or frantic in pace.

Idiom: live life in the fast lane

colloq
To have a lifestyle full of high excitement, expensive enjoyment and glamour.

Idiom: play fast and loose

To behave irresponsibly or unreliably.
Thesaurus: behave recklessly, run wild, be careless, misbehave.

Idiom: pull a fast one

colloq
To cheat or deceive.

Etymology: Anglo-Saxon fæst fixed or firm.

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fast²
verb

intr
fasted, fasting
1. To go without food, or restrict one's diet, especially as a religious discipline.

noun

1. A period of fasting. See Lent, Ramadan, Yom Kippur.

Derivative: fast-day
noun

Derivative: faster
noun

Derivative: fasting
noun

Etymology: Anglo-Saxon fæstan.