Other forms: faster, fastest, fasting, fasts, fasted
Fast means moving with great speed — a fast car, a fast runner, a fast train. It is the adverb as well, with no -ly added: you drive fast, you talk too fast, the week went fast.
There is an older fast hiding inside the word, and it means the opposite of moving: fixed, firm, not going anywhere. That is the fast in stuck fast, hold fast and fast asleep, and it is why the verb fasten exists and why a colour that will not wash out is colourfast. A third fast belongs to food: to fast is to go without eating, and breakfast is the meal that breaks it. Two small traps. The comparison is faster and fastest, never 'more fast'. And a fast clock is not a good clock — it is running ahead of the real time.
1adjectivefastMoving, or able to move, at great speed.~86%
“The train is fast enough to get you there before lunch.”
synonyms: quick, rapid, swift
2adverbgreatAt great speed.~8%
“He was walking too fast for me to keep up.”
3adjectivefirmlyFirmly fixed in place and hard to move.~2%
“The door was stuck fast in its frame.”
4verbfoodTo go without food for a period, for religious or health reasons.~2%
“Many people fast from sunrise to sunset during the month.”
5adjectiveclockOf a clock or watch, showing a time later than the real one.~2%
“My watch is five minutes fast.”
Shares are an estimate: a language model read 12 sentences found in the wild and placed 12 of them on a sense — a count of our sample, not a measurement of English.
Also accepted in games: quick
In Old English, fæst meant firm and secure, the sense still alive in fasten and in stuck fast. Speed arrived sideways and late: the adverb went first, the way we still say 'to run hard', and the adjective followed it. Latin pulled the same trick, turning rapiō, 'to snatch', into rapidus, 'quick'.
Proto-Indo-European
*peh₂ǵ-
Old English
fæst
Middle English
fast
English, today
fast
From Middle English fast, from Old English fæst. 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”).
Etymology from Wiktionary, CC BY-SA