fast.
Firmly or securely fixed in place; stable.
Meaning & usage
Firmly or securely fixed in place; stable.
That rope is dangerously loose. Make it fast!
Firm against attack; fortified by nature or art; impregnable; strong.
Steadfast, with unwavering feeling. (Now mostly in set phrases like fast friend(s).)
Moving with great speed, or capable of doing so; swift, rapid; light.
I am going to buy a fast car.
Moving with great speed, or capable of doing so; swift, rapid; light. 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.
Of a place, characterised by business, hustle and bustle, etc.
Causing unusual rapidity of play or action.
a fast racket, or tennis court
a fast track
Able to transfer data in a short period of time.
Deep or sound (of sleep); fast asleep (of people).
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.
Tenacious; retentive.
Having an extravagant lifestyle or immoral habits.
a fast woman
Uncharacteristically mature or promiscuous for one's age.
Ahead of the correct time or schedule.
There must be something wrong with the hall clock. It is always fast.
More sensitive to light than average.
Where this word comes from
Etymology tree Proto-Germanic *fastuz Proto-West Germanic *fast Old English fæst Middle English fast English fast 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”). Also compare close meaning change from Latin rapiō (“to snatch”) to Latin rapidus (“rapid, quick”), from Irish sciob (“to snatch”) to Irish sciobtha (“quick”).
A train that calls at only some stations it passes between its origin and destination, typically just the principal stations.
Where this word comes from
Etymology tree Proto-Germanic *fastuz Proto-West Germanic *fast Old English fæst Middle English fast English fast 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”). Also compare close meaning change from Latin rapiō (“to snatch”) to Latin rapidus (“rapid, quick”), from Irish sciob (“to snatch”) to Irish sciobtha (“quick”).
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.
Deeply or soundly .
The princess was sleeping fast, and her servants were fast asleep too.
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.
Quickly, with great speed; within a short time .
Do it as fast as you can.
Ahead of the correct time or schedule.
I think my watch is running fast.
Where this word comes from
From Middle English fast, faste, from Old English fæste, from fæst + -e (adverb-forming suffix).
To practice religious abstinence, especially from food.
To reduce or limit one's nutrition intake for medical or health reasons, to diet.
To cause (a person or animal) to abstain, especially from eating.
Where this word comes from
From Middle English fasten, from Old English fæstan (“to fast”), from Proto-West Germanic *fastēn, from Proto-Germanic *fastāną (“to fast”), from the same root as Proto-Germanic *fastijaną (“to 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).
The act or practice of fasting, religious abstinence from food.
Any of the fasting periods in the liturgical year.
Where this word comes from
From Middle English faste, fasten, from Old English fæsten (“fast, fasting”), from Proto-West Germanic *fastuni, from Proto-Germanic *fastu(b)nją (“fast, fasting”). Cognate with Old Frisian festene, feste (Modern West Frisian fêsten, fêste), Middle Dutch vastene (Modern Dutch vasten), Middle Low German vastene (Modern German Low German Fasten), German Faste, Fasten (“fast, fasting”), Gothic 𐍆𐌰𐍃𐍄𐌿𐌱𐌽𐌹 (fastubni, “fasting”). Possibly merged with Old Norse fasta (“fast, fasting”), whence also Danish faste (“fast, fasting”), Swedish fasta (“fast, fasting”).
Ellipsis of stand fast, a warning not to pass between the arrow and the target.
Where this word comes from
Etymology tree Proto-Germanic *fastuz Proto-West Germanic *fast Old English fæst Middle English fast English fast 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”). Also compare close meaning change from Latin rapiō (“to snatch”) to Latin rapidus (“rapid, quick”), from Irish sciob (“to snatch”) to Irish sciobtha (“quick”).
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Definitions, grammatical labels, IPA, etymology and examples: Wiktionary contributors, extracted by Kaikki / Wiktextract. Adapted under CC BY-SA 4.0. Selected fields and authored examples are shown; third-party quotations and audio are omitted. See contributor history.
Last enriched 2026-09-10. Definitions are in English. Romanizations are shown when supplied by the source; syllable estimates are omitted for unsupported scripts.