# fast

> English word · Adjective · IPA /fɑːst/ · frequency rank #767

## Definitions
1. Firmly or securely fixed in place; stable.
2. Firm against attack; fortified by nature or art; impregnable; strong.
3. Steadfast, with unwavering feeling. (Now mostly in set phrases like fast friend(s).)
4. Moving with great speed, or capable of doing so; swift, rapid; light.
5. Moving with great speed, or capable of doing so; swift, rapid; light.
6. Of a place, characterised by business, hustle and bustle, etc.
7. Causing unusual rapidity of play or action.
8. Able to transfer data in a short period of time.
9. Deep or sound (of sleep); fast asleep (of people).
10. Not running or fading when subjected to detrimental conditions such as wetness or intense light; permanent.
11. Tenacious; retentive.
12. Having an extravagant lifestyle or immoral habits.
13. Uncharacteristically mature or promiscuous for one's age.
14. Ahead of the correct time or schedule.
15. More sensitive to light than average.

## Etymology
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”).

## Easily confused with
- **FS** (https://plainspell.com/en/vs/fast-vs-fs)
- **fit** (https://plainspell.com/en/vs/fast-vs-fit)
- **fat** (https://plainspell.com/en/vs/fast-vs-fat)
- **fax** (https://plainspell.com/en/vs/fast-vs-fax)
- **FFS** (https://plainspell.com/en/vs/fast-vs-ffs)
- **fay** (https://plainspell.com/en/vs/fast-vs-fay)
- **FSA** (https://plainspell.com/en/vs/fast-vs-fsa)
- **FBS** (https://plainspell.com/en/vs/fast-vs-fbs)
- **FSB** (https://plainspell.com/en/vs/fast-vs-fsb)
- **FES** (https://plainspell.com/en/vs/fast-vs-fes)
- **FIS** (https://plainspell.com/en/vs/fast-vs-fis)
- **FET** (https://plainspell.com/en/vs/fast-vs-fet)
- **fut** (https://plainspell.com/en/vs/fast-vs-fut)
- **felt** (https://plainspell.com/en/vs/fast-vs-felt)
- **feet** (https://plainspell.com/en/vs/fast-vs-feet)
- **fish** (https://plainspell.com/en/vs/fast-vs-fish)
- **foot** (https://plainspell.com/en/vs/fast-vs-foot)
- **flat** (https://plainspell.com/en/vs/fast-vs-flat)
- **fort** (https://plainspell.com/en/vs/fast-vs-fort)
- **fate** (https://plainspell.com/en/vs/fast-vs-fate)

## Common misspellings (5)
`afst`, `fasst`, `fastt`, `ffast`, `fsat`

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/fast