fast

Etymology 1

From Middle English fast, fest, from Old English fæst (“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”).

adj

1. (dated) Firmly or securely fixed in place; stable.
   That rope is dangerously loose. Make it fast!
2. Firm against attack; fortified by nature or art; impregnable; strong.
3. (of people) Steadfast, with unwavering feeling. (Now mostly in set phrases like fast friend(s).)
   I still hear you sayin', "Dear one, hold me fast" 1933, Will Hudson, Irving Mills, Eddy DeLange, Moonglow
4. Moving with great speed, or capable of doing so; swift, rapid.
   I am going to buy a fast car.
   1. (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).
      Plutonium-240 has a much higher fission cross-section for fast neutrons than for thermal neutrons.
5. Of a place, characterised by business, hustle and bustle, etc.
   Sydney is a fast city, and the pace is becoming increasingly more frantic. 1968, Carl Ruhen, The Key Club, Sydney: Scripts, page 15
6. Causing unusual rapidity of play or action.
   a fast racket, or tennis court
   a fast track
   a fast billiard table
   a fast dance floor
7. (computing, of a piece of hardware) Able to transfer data in a short period of time.
8. Deep or sound (of sleep); fast asleep (of people).
9. (of dyes or colours) Not running or fading when subjected to detrimental conditions such as wetness or intense light; permanent.
   All the washing has come out pink. That red tee-shirt was not fast.
10. (obsolete) Tenacious; retentive.
11. (dated) Having an extravagant lifestyle or immoral habits.
    a fast woman
    […] we remember once hearing a fast man suggest that they were evidently "nobs who had overdrawn the badger by driving fast cattle, and going it high" — the exact signification of which words we did not understand […] 1852, John Swaby, Physiology of the Opera, page 74
    Had Senator Wilson won the unenviable reputation of being a fast man—a lover of wine, or had he shown himself to the public in a state of inebriety, unable to stand erect in Fanueil Hall for instance, leaning upon the desk to “maintain the center of gravity,” and uttering words that fell sprawling in “muddy obscurity” from lips redolent of rum, rendering it necessary for a prompter and an interpreter to sculpture his speech into symmetry for the public ear and the public press, he would have been pelted from his high office with the indignant ballots of his constituents. 1867, George W. Bungay, “Temperance and its Champions”, in The Herald of Health and Journal of Physical Culture, volume I, page 277
    You're alone with her at last / And you're waiting 'til you think the time is right / Cause you've heard she's pretty fast / And you're hoping that she'll give you some tonight. 1979, Doug Fieger, Good Girls Don't
12. Ahead of the correct time or schedule.
    There must be something wrong with the hall clock. It is always fast.
13. (of photographic film) More sensitive to light than average.

adv

1. In a firm or secure manner, securely; in such a way as not to be moved; safe, sound .
   Hold this rope as fast as you can.
2. (of sleeping) Deeply or soundly .
   He is fast asleep.
3. Immediately following in place or time; close, very near .
   The horsemen came fast on our heels.
   Fast by the sturdy batsman the ball unheeded sped. / That ain't my style, said Casey. Strike one, the umpire said.
4. Quickly, with great speed; within a short time .
   Do it as fast as you can.
   Faster than a speeding bit, the internet upended media and entertainment companies. Piracy soared, and sales of albums and films slid. Newspapers lost advertising and readers to websites. Stores selling books, CDs and DVDs went bust. Doomsayers predicted that consumers and advertisers would abandon pay-television en masse in favour of online alternatives. 2013-08-17, “Pennies streaming from heaven”, in The Economist, volume 408, number 8849
5. Ahead of the correct time or schedule.
   I think my watch is running fast.

noun

1. (Britain, rail transport) A train that calls at only some stations it passes between its origin and destination, typically just the principal stations
   , fast train

intj

1. (archery) Short for "stand fast", a warning not to pass between the arrow and the target

Etymology 2

From Middle English fasten, from Old English fæstan (verb), Old English fæsten (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 Gothic 𐍆𐌰𐍃𐍄𐌰𐌽 (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 German fasta likely existed in the 8th century (shift to neuter Old High German fasten from the 9th century, whence modern German Fasten). The Old English noun originally had the sense "fortress, enclosure" and takes the religious sense only in late Old English, perhaps influenced by Old Norse fasta. 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

1. (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?
   It is at the core of the Vision Quest, the solitary period of fasting and closeness to the earth to discover one's life path and purpose. 2007, John Zerzan, Silence, page 3
2. (intransitive) To reduce or limit one's nutrition intake for medical or health reasons, to diet.
   The ideal would be to fast in a situation where you are not tempted by food 1977, Suza Norton, “To get the most benefit from fasting use a body-building diet”, in Yoga Journal, Jul-Aug 1977, p. 40
   After the equilibration period, the rats designated for deprivation studies were made to fast for 24, 48, 72, or 96 hr according to experimental design. 1983, Experimental Lung Research, volumes 5-6, Informa healthcare, page 134
3. (transitive) (academic) To cause a person or animal to abstain, especially from eating.
   At 11 weeks of age, all mice were fasted overnight and underwent gallbladder ultrasonography to determine ejection fraction. Walker et al. (2007)
   Kittens, when fasted overnight, were not hypoglycemic (<60 mg/dl). Semick et al. (2018)

noun

1. 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?
   anciently a change of diet was not reckoned a fast; but it consisted in a perfect abstinence from all sustenance for the whole day till evening. 1878, Joseph Bingham, The Antiquities of the Christian Church, volume 2, page 1182
2. 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). And so may we enter the Fasts at hand, beginning Lent the 30th. day of the Month Mechir