Why do people say "I want it done fast"?

Fast is modifying 'done' which is the past tense of a verb. Verbs are modified by adverbs - which end with 'ly'. They should say "I want it done quickly".

A similar mistake arises about cars (and other the things). It may be a fast car, but you drive it quickly - you do not drive it fast.

I discussed this with a professor of computing who said "It doesn't matter - it's common usage". Common or not, it is wrong. Yes, or no?

Does anyone care anymore? Does anyone know anymore?

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    Not all adverbs end in -ly; fast is an adverb. See dictionary. If somebody says "I want it done quick" (which they do), you might have reason to complain. Commented Sep 9, 2016 at 12:41
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    This question has an answer here. Adverbs like quick are "flat adverbs" and they have a long history of usage. Commented Sep 9, 2016 at 12:47
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    The point is that "fast" doesn't have a related adverb ending in ly; (there's no *fastly"). So it can belong to both the adjective and adverb categories depending on its function in the clause: " He owned a fast car" (adjective) and "He drove fast" (adverb).
    – BillJ
    Commented Sep 9, 2016 at 12:57
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    @MarkTucker Common usage and correctness aren't mutually exclusive... Don't come to EL&U asking for affirmation of your own opinions. Come to EL&U to ask for meaningful answers (that may prove you wrong; oops you might learn something). Meaningful answers have been given for this question and they're well-documented and justified.
    – user109263
    Commented Sep 9, 2016 at 14:33
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    On another note, I think one of the best examples of a flat adverb (offered in NVZ's answer) is hard. Pushing the door hard and hardly pushing the door are two very different things.
    – user109263
    Commented Sep 9, 2016 at 14:34

1 Answer 1


Fast is an adjective, and an adverb as well. — ODO

adjective 1. Moving or capable of moving at high speed
"a fast and powerful car"

adverb 1. At high speed
"he was driving too fast"

Adverbs that don't use the normal -ly suffix are called flat adverbs. — Wikipedia

A flat adverb is an adverb that assumes the form of a related adjective, most often when words ending in -ly are used without the -ly. Though once quite common, flat adverbs have been largely phased out by their -ly counterparts. This shift owes to 18th-century grammarians who insisted that adverbs end in -ly. Nonetheless, flat adverbs are preferred in some idioms, as in "take it easy" and "sleep tight".

Mark Nichol of Daily Writing Tips lists some flat adverbs: bright, clean, close, deep, far, fast, flat, hard, kind, quick, right, sharp, slow, soon, and tough.

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