From Middle Englishfast, fest, from Old Englishfæst(“firm, secure”), from Proto-West Germanic*fast, from Proto-Germanic*fastuz; see it for cognates and further etymology.
The development of “rapid” from an original sense of “secure” apparently happened first in the adverb and then transferred to the adjective; compare hard in expressions like “to run hard”. The original sense of “secure, firm” is now slightly archaic, but retained in the related fasten(“make secure”). Also compare close meaning change from Latinrapiō(“to snatch”) to Latinrapidus(“rapid, quick”), from Irishsciob(“to snatch”) to Irishsciobtha(“quick”).
Adjective
fast (comparativefaster, superlativefastest)
(dated) Firmly or securely fixed in place; stable. [from 9th c.]
Firm against attack; fortified by nature or art; impregnable; strong.
Synonyms:fortified, impenetrable
Antonyms:penetrable, weak
(of people) Steadfast, with unwavering feeling. (Now mostly in set phrases like fast friend(s).) [from 10th c.]
Moving with great speed, or capable of doing so; swift, rapid. [from 14th c.]
Synonyms:quick, rapid, speedy
(nuclear physics, of a neutron) Having a kinetic energy between 1 million and 20 million electron volts; often used to describe the energy state of free neutrons at the moment of their release by a nuclear fission or nuclear fusion reaction (i.e., before the neutrons have been slowed down by anything).
Of a place, characterised by business, hustle and bustle, etc.
Causing unusual rapidity of play or action.
(computing, of a piece of hardware) Able to transfer data in a short period of time.
Deep or sound (of sleep); fast asleep (of people). [16th–19th c.]
Synonyms:deep, sound
Antonym:light
(of dyes or colours) Not running or fading when subjected to detrimental conditions such as wetness or intense light; permanent. [from 17th c.]
Synonym:colour-fast
(obsolete) Tenacious; retentive.
(dated) Having an extravagant lifestyle or immoral habits. [from 18th c.]
Ahead of the correct time or schedule. [from 19th c.]
Synonyms:ahead, (as in “the clock is gaining x minutes per hour/day”)gain
Antonyms:behind, slow
(of photographic film) More sensitive to light than average. [from 20th c.]
Usage notes
In the context of nuclear reactors or weaponry, fission-spectrum neutrons (neutrons with the spectrum of energies produced by nuclear fission) are frequently referred to as fast neutrons, even though the majority of fission-spectrum neutrons have energies below the 1-million-electron-volt cutoff.
Synonyms
(occurring or happening within a short time):quick, rapid, speedy, swift
(capable of moving with great speed): see also Thesaurus:speedy
(rapidly consents to sexual activity):easy, slutty; see also Thesaurus:promiscuous
(firmly or securely fixed in place): see also Thesaurus:tight
Antonyms
(antonym(s) of "occurring or happening within a short time"):slow
Derived terms
Translations
Adverb
fast (comparativefaster, superlativefastest)
In a firm or secure manner, securely; in such a way as not to be moved; safe, sound [from 10th c.].
Synonyms:firmly, securely, tightly
Antonym:loosely
(of sleeping) Deeply or soundly [from 13th c.].
Synonym:deeply
Antonym:lightly
Immediately following in place or time; close, very near [from 13th c.].
Quickly, with great speed; within a short time [from 13th c.].
Synonyms:quickly, rapidly, speedily, swiftly
Antonym:slowly
Ahead of the correct time or schedule.
Synonym:ahead
Antonym:behind
Translations
Noun
fast (pluralfasts)
(British, rail transport) A train that calls at only some stations it passes between its origin and destination, typically just the principal stations
Synonyms:express, express train, fast train
Antonyms:local, slow train, stopper
Translations
Interjection
fast
(archery) Short for "stand fast", a warning not to pass between the arrow and the target
Antonym:loose
Translations
Etymology 2
From Middle Englishfasten, from Old Englishfæstan (verb), Old Englishfæsten (noun) from
Proto-Germanic*fastāną(“fast”), from the same root as Proto-Germanic*fastijaną(“fasten”), derived from *fastuz, and thereby related to Etymology 1.
The religious sense is presumably introduced in the Gothic church, from Gothic𐍆𐌰𐍃𐍄𐌰𐌽(fastan, “hold fast (viz. to the rule of abstinence)”). This semantic development is unique to Gothic, the term glosses Greek νηστεύω(nēsteúō), Latin ieiuno which do not have similar connotations of "holding fast".
The feminine noun Old High Germanfasta likely existed in the 8th century (shift to neuter Old High Germanfasten from the 9th century, whence modern GermanFasten).
The Old English noun originally had the sense "fortress, enclosure" and takes the religious sense only in late Old English, perhaps influenced by Old Norsefasta.
The use for reduced nutrition intake for medical reasons or for weight reduction develops by the mid-1970s, back-formed from the use of the verbal noun fasting in this sense (1960s).
Verb
fast (third-person singular simple presentfasts, present participlefasting, simple past and past participlefasted)
(intransitive) To practice religious abstinence, especially from food.
1677 George Fox, The Hypocrites Fast and Feast Not God's Holy Day, p. 8 (paraphrasing Matthew 6:16-18).
And is it not the Command of Christ, that in their Fast they should not appear unto men to fast?
(intransitive) To reduce or limit one's nutrition intake for medical or health reasons, to diet.
(transitive)(academic) To cause a person or animal to abstain, especially from eating.
Walker et al. (2007)
At 11 weeks of age, all mice were fasted overnight and underwent gallbladder ultrasonography to determine ejection fraction.
Semick et al. (2018)
Kittens, when fasted overnight, were not hypoglycemic (<60 mg/dl).
Translations
Noun
fast (pluralfasts)
The act or practice of fasting, religious abstinence from food
1677 George Fox, The Hypocrites Fast and Feast Not God's Holy Day, p. 8 (paraphrasing Matthew 6:16-18).
And is it not the Command of Christ, that in their Fast they should not appear unto men to fast?
One of the fasting periods in the liturgical year
1662 Peter Gunning, The Holy Fast of Lent Defended Against All Its Prophaners: Or, a Discourse, Shewing that Lent-Fast was First Taught the World by the Apostles (1677 [1662]), p. 13 (translation of the Paschal Epistle of Theophilus of Alexandria).
Derived terms
Translations
References
“fast”, in The Century Dictionary[…], New York, N.Y.: The Century Co., 1911, →OCLC.