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[fast, fahst] /fæst, fɑst/
verb (used without object)
to abstain from all food.
to eat only sparingly or of certain kinds of food, especially as a religious observance.
verb (used with object)
to cause to abstain entirely from or limit food; put on a fast:
to fast a patient for a day before surgery.
an abstinence from food, or a limiting of one's food, especially when voluntary and as a religious observance; fasting.
a day or period of fasting.
Origin of fast2
before 1000; Middle English fasten, Old English fæstan; cognate with German fasten, Gothic fastan, Old Norse fasta
Related forms
unfasting, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for fasting
Contemporary Examples
Historical Examples
  • Festival of the ancient gods, for which preparation was made the day before by fasting.

  • Why should fasting occupy a place in the disciplines of religion?

  • With them we sometimes find the lawful owner, the grub-worm of the Bee, but stunted and thin with fasting.

    Insect Adventures J. Henri Fabre
  • When we got to our third day's fasting we were keen enough for a meal.

    An Explorer's Adventures in Tibet A. Henry Savage Landor
  • Here he at once adopted that spirit of fasting and penance which knew no moderation and with him became fanaticism.

    Glories of Spain Charles W. Wood
British Dictionary definitions for fasting


acting or moving or capable of acting or moving quickly; swift
accomplished in or lasting a short time: fast work, a fast visit
(prenominal) adapted to or facilitating rapid movement: the fast lane of a motorway
requiring rapidity of action or movement: a fast sport
(of a clock, etc) indicating a time in advance of the correct time
given to an active dissipated life
of or characteristic of such activity: a fast life
not easily moved; firmly fixed; secure
firmly fastened, secured, or shut
steadfast; constant (esp in the phrase fast friends)
(sport) (of a playing surface, running track, etc) conducive to rapid speed, as of a ball used on it or of competitors playing or racing on it
that will not fade or change colour readily: a fast dye
  1. proof against fading: the colour is fast to sunlight
  2. (in combination): washfast
  1. requiring a relatively short time of exposure to produce a given density: a fast film
  2. permitting a short exposure time: a fast shutter
(cricket) (of a bowler) characteristically delivering the ball rapidly
(informal) glib or unreliable; deceptive: a fast talker
(archaic) sound; deep: a fast sleep
(informal) a deceptive or unscrupulous trick (esp in the phrase pull a fast one)
fast worker, a person who achieves results quickly, esp in seductions
quickly; rapidly
soundly; deeply: fast asleep
firmly; tightly
in quick succession
in advance of the correct time: my watch is running fast
in a reckless or dissipated way
(archaic) fast by, fast beside, close or hard by; very near
(informal) play fast and loose, to behave in an insincere or unreliable manner
(archery) (said by the field captain to archers) stop shooting!
Word Origin
Old English fæst strong, tight; related to Old High German festi firm, Old Norse fastr


(intransitive) to abstain from eating all or certain foods or meals, esp as a religious observance
  1. an act or period of fasting
  2. (as modifier): a fast day
Derived Forms
faster, noun
Word Origin
Old English fæstan; related to Old High German fastēn to fast, Gothic fastan
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for fasting



Old English fæst "firmly fixed, steadfast, secure, enclosed," probably from Proto-Germanic *fastuz (cf. Old Frisian fest, Old Norse fastr, Dutch vast, German fest), from PIE root *past- "firm" (cf. Sanskrit pastyam "dwelling place").

The adverb meaning "quickly, swiftly" was perhaps in Old English, or from Old Norse fast, either way developing from the sense of "firmly, strongly, vigorously" (cf. to run hard means to run fast; also compare fast asleep), or perhaps from the notion of a runner who "sticks" close to whatever he is chasing.

The sense of "living an unrestrained life" (usually of women) is from 1746 (fast living is from 1745). Fast buck recorded from 1947; fast food is first attested 1951. Fast-forward first recorded 1948. Fast lane is by 1966; the fast track originally was in horse-racing (1934); figurative sense by 1960s. To fast talk someone (v.) is recorded by 1946.


Old English fæstan "to fast" (as a religious duty), from Proto-Germanic *fastejan (cf. Old Frisian festia, Old High German fasten, German fasten, Old Norse fasta), from the same root as fast (adj.).

The original meaning was "hold firmly," and the sense evolution is via "firm control of oneself," to "holding to observance" (cf. Gothic fastan "to keep, observe," also "to fast"). Presumably the whole group is a Germanic translation of Medieval Latin observare "to fast." Related: Fasted; fasting.


Old English fæstan, festen, or Old Norse fasta; from the root of fast (v.).

Online Etymology Dictionary, © 2010 Douglas Harper
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fasting in Medicine

fast 1 (fāst)
adj. fast·er, fast·est

  1. Acting, moving, or being capable of acting or moving quickly.

  2. Accomplished in relatively little time.

  3. Exhibiting resistance to change. Used especially of stained microorganisms that cannot be decolorized.

  4. Firmly fixed or fastened.

fast 2
v. fast·ed, fast·ing, fasts

  1. To abstain from food.

  2. To eat little or abstain from certain foods, especially as a religious discipline.

  1. The act or practice of abstaining from or eating very little food.

  2. A period of such abstention or self-denial.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Slang definitions & phrases for fasting



Morally lax; libertine: on Long Island with the fast younger married set (1859+)

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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Related Abbreviations for fasting


flow actuated sediment trap
Food Allergy Survivors Together
fore-aft scanning technique
The American Heritage® Abbreviations Dictionary, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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fasting in the Bible

The sole fast required by the law of Moses was that of the great Day of Atonement (q.v.), Lev. 23:26-32. It is called "the fast" (Acts 27:9). The only other mention of a periodical fast in the Old Testament is in Zech. 7:1-7; 8:19, from which it appears that during their captivity the Jews observed four annual fasts. (1.) The fast of the fourth month, kept on the seventeenth day of Tammuz, the anniversary of the capture of Jerusalem by the Chaldeans; to commemorate also the incident recorded Ex. 32:19. (Comp. Jer. 52:6, 7.) (2.) The fast of the fifth month, kept on the ninth of Ab (comp. Num. 14:27), to commemorate the burning of the city and temple (Jer. 52:12, 13). (3.) The fast of the seventh month, kept on the third of Tisri (comp. 2 Kings 25), the anniversary of the murder of Gedaliah (Jer. 41:1, 2). (4.) The fast of the tenth month (comp. Jer. 52:4; Ezek. 33:21; 2 Kings 25:1), to commemorate the beginning of the siege of the holy city by Nebuchadnezzar. There was in addition to these the fast appointed by Esther (4:16). Public national fasts on account of sin or to supplicate divine favour were sometimes held. (1.) 1 Sam. 7:6; (2.) 2 Chr. 20:3; (3.) Jer. 36:6-10; (4.) Neh. 9:1. There were also local fasts. (1.) Judg. 20:26; (2.) 2 Sam. 1:12; (3.) 1 Sam. 31:13; (4.) 1 Kings 21:9-12; (5.) Ezra 8:21-23: (6.) Jonah 3:5-9. There are many instances of private occasional fasting (1 Sam. 1:7: 20:34; 2 Sam. 3:35; 12:16; 1 Kings 21:27; Ezra 10:6; Neh. 1:4; Dan. 10:2,3). Moses fasted forty days (Ex. 24:18; 34:28), and so also did Elijah (1 Kings 19:8). Our Lord fasted forty days in the wilderness (Matt. 4:2). In the lapse of time the practice of fasting was lamentably abused (Isa. 58:4; Jer. 14:12; Zech. 7:5). Our Lord rebuked the Pharisees for their hypocritical pretences in fasting (Matt. 6:16). He himself appointed no fast. The early Christians, however, observed the ordinary fasts according to the law of their fathers (Acts 13:3; 14:23; 2 Cor. 6:5).

Easton's 1897 Bible Dictionary
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Idioms and Phrases with fasting
The American Heritage® Idioms Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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