I have read many books say that

they ran fast.

But that sounds wrong compared to

they ran quickly.

Which should it be?

  • 1
    Depends on the context.
    – NVZ
    Commented Feb 20, 2016 at 17:56
  • There would often be a different nuance. For example, She quickly ran to the shop to get some milk would normally focus on the fact that getting the milk didn't take long (perhaps implying the shop is very close, and it's worth noting one can say this even if all she did was walk quickly). On the other hand, She ran fast to the shop to get some milk focuses more on the high speed of her running (though idiomatically it's not a very likely thing to say). Commented Feb 20, 2016 at 18:01
  • Are you asking why it is not "fastly"? 'cuz that doesn't exist. Commented Feb 20, 2016 at 18:43

2 Answers 2


Your first example is fine (as is your second) even though "fast" looks like an adjective modifying a verb (adjectives, of course, can't normally modify verbs; only adverbs can do that, but read on).

English has several adjectives that have corresponding adverbs that don't take the -ly suffix. Words like "fast", "late" and "hard" can certainly be used either as adjectives or as adverbs, without the -ly (she drove fast; let's arrive late; they tried hard.

By all means use "quickly" if you wish, but don't do it because you think "fast" is wrong, because it isn't.


Quickly. Adverb, modifies a verb. Not fast, an adjective that modifies a noun.

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