How to say "fast" in Japanese
Choosing the right word
- 早いはやいi-adjectiveThe everyday adjective for speed: a fast car, a fast runner, work done fast. When you mean quick, rapid or swift in the ordinary sense, this is the word you want.
- prenominal modifierThe English loanword. It is not the adjective you reach for in ordinary sentences; it turns up chiefly inside borrowed set expressions, and 早い covers everyday 'fast'.
- adverb (with と)Only for the idiom 'fast asleep': a mimetic word meaning to sleep soundly and deeply. It has nothing to do with speed, so never use it for fast movement.
- 断食だんじきnoun, suru verb, intransitive verbThe noun 'fast' in the sense of going without food, as in religious or health fasting. Unrelated to speed; if you mean quick, you want 早い instead.
- 足早あしばやna-adjectiveDescribes a quick, brisk pace on foot — someone walking fast, hurrying along. Narrower than 早い: it fits walking or a person's gait, not speed in general.
For speed in general use 「早い」; 足早 is for a brisk walking pace; 「ぐっすり」 appears only in 'fast asleep'; 断食 is the noun 'fast' meaning going without food; 「ファースト」 is the loanword, mostly in set phrases.
Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only
Japanese equivalents
See also
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