It would make sense if both of these sentences were grammatically correct; but is anything different between them meaning-wise?

He acted very strange when I told him about the missing amulet.

He acted strangely about the whole deal.

What difference is there between using an adverb here and using an adjective?

3 Answers 3


Acted is a verb which can take an adjective in what looks like a modifying position. Some verbs are like that; they are called copular (or copulative or copula) verbs. Let's consider the verb look, where using an adjective and an adverb produce different meanings.

For some meanings, you have to use nice:

John looked very nice in his new clothes.
*John looked very nicely in his new clothes.

For others, you have to use nicely.

John looked at me very nicely.
*John looked at me very nice.

In the first example, very nice is in some sense modifying John, while in the second, very nicely is modifying looked.

For the verb act, you can use either an adjective or an adverb:

John acted very strange.
John acted very strangely.

and the meaning isn't any different between these two sentences (or at least not much). I would say that in the first sentence, John is acting as if he was very strange, and in the second sentence, John's actions are very strange. In this case, the meanings end up being the same. But consider:

John acted very quiet.
John acted very quietly.

Now, these mean different things. In the first, John is simply being quiet. In the second, John is doing something and trying hard not to call attention to it.

  • Yes, I think I get similar differences of readings too: using the adjective implies a bit more that the manner in which they were acting was more of a permanent trait. Whereas e.g. "John was acting strangely" can imply "I know John isn't strange, but on that particular occasion his actions seemed strange". Jul 2, 2011 at 15:34
  • @Neil: I wasn't trying to say that there was a difference in meanings between the two sentences (although I think I perceive the same very subtle distinction that you do). I was trying to explain how the two different grammatical constructions resulted in the same meaning. Jul 2, 2011 at 17:10
  • Ah OK sorry I misunderstood slightly: I thought your point was "the first sentence has this interpretation, the second this, but it boils down to roughly the same thing". Jul 2, 2011 at 18:16
  • @Neil: I think you did understand; I misunderstood your comment, then. Jul 2, 2011 at 18:24

It is not uncommon for people to use the adjectival form of a word where you might expect an adverb. Indeed, this is one of the biggest sources of confusion for native and non-native speakers alike.

Certainly you could say, without triggering the Pedant-O-Meter:

He acted hostile toward me.


He acted hostilely toward me.

would trigger comments from just about anybody, although the sentence does seem to require an adverbial form.

Now consider the following:

I felt bad for you.
I felt badly for you.

Many people prefer the latter, thinking it's grammatically correct, but the fact is it literally implies some kind of defect on the part of the speaker's ability to feel. Turn it around: Do you ever feel "goodly" for someone?

To sum up: Informally, you can use either, and most people would say a person acted strange (in everyday speech). In more formal situations, it would be prudent to use strangely instead.

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    I think you should be able to use either in any situation except maybe for an English class with a teacher who is very strict about grammar but doesn't understand it very well. Jul 2, 2011 at 14:55
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    @Robusto: I feel well for you...
    – Daniel
    Jul 2, 2011 at 15:14
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    Agree with Peter -- any "rule" that an adjective is outlawed here is spurious; they're different constructions. (N.B. "act" can also take a noun complement: "He was acting the idiot".) Jul 2, 2011 at 15:36
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    @NeilCofey: Robusto didn't say "outlawed"; he meant that "act strange" sounds slightly informal. Jul 2, 2011 at 19:57

This is an idiom that seems common in US English. Speakers of that dialect commonly substitute adjectives for adverbs. There isn't any extra meaning attached to this, it is just a dialectic peculiarity.

In fact, in the US use of an adverb in some situations sounds a little formal. For example:

This is real good coffee

This is really good coffee

You will hear the first commonly in the US, and the second sounds formal. In the UK the first sounds "American" and the second is perfunctory.

I don't know about other dialects, US and UK are the ones I am familiar with.

  • 1
    “Really good coffee” is not formal in AmE at all, except perhaps in certain dialects. “Real good coffee”, on the other hand, is decidedly informal. Also, adverbial substitution for adjectives is not what’s at play here—the two sentences in the question are simply different structures, and they are both equally valid and allowed in both AmE and BrE. Apr 14, 2014 at 8:50

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