When can we use nouns like adjectives? For example “Apple tree” where “Apple” functions as an adjective. But I saw the following as an example of a grammatically wrong compound on a website:

When they fight against other opponent teams.

Why is "opponent teams" grammatically wrong but is "Apple tree" correct?

  • Yes, I mean a "modifier" which functions like an adjective. My question exactly is that; Why "apple tree" is possible but not "opponent team"? Is there any rule?
    – shapoor
    Commented Aug 17, 2020 at 16:11
  • 1
    @shapoor They are called attributive nouns, and they function as if they were adjectives. Or, in other words, they function adjectivally. The reason we don't say opponent teams is because there is already another word that serves the same function: opposing teams. In this case, opposing is actually a verb, but it's being used adjectivally. There is no reason to use a noun in that way if there's already something else that's functioning adjectivally for it. Commented Aug 17, 2020 at 16:30
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    @shapoor That aside, "because English." The adjectival use of a noun (or verb, or not) is arbitrary. Things sound right simply because they are commonly used. Opponent teams is not commonly used—so it sounds wrong. Commented Aug 17, 2020 at 16:32
  • Can you cite the relevant webpage? I can see some reason to object to that phrasing on semantic grounds (because it makes "they" an opponent team, just like the others, and are they opponents of themselves?). I don't see anything grammatically wrong with the structure. Commented Aug 17, 2020 at 16:40
  • Look, be clear about this. Don't even use the word 'adjective' when you're talking about nouns modifying other nouns (or any other category of word). 'Adjectivally' is not a function, so don't use the term. Nouns that function as modifiers are not adjectives, and they don't behave like adjectives. Other than the fact that like adjectives they modify other words, there is no similarity.
    – BillJ
    Commented Aug 17, 2020 at 17:14

2 Answers 2


This example:

When they fight against other opponent teams.

is not grammatically wrong.
(Except that it's not a complete sentence. It could still be the answer to a question: "When do they lose?")

I've consulted Merriam-Webster, American Heritage, and Cambridge dictionaries, which all show an adjective sense for the word, with the meaning of "opposing".

Here is one of the definitions:
Merriam-Webster "opponent"
opponent adjective
1 : antagonistic, opposing
2 : situated in front

Answer updated 8/18/2020.

While "opponent" definitely exists as an adjective, it occurs mostly in antiquated texts, and in modern texts on neurobiology, optics, sociology and psychology. It occurs in modified form ("highly opponent", "fully opponent"), and as a predicate adjective ("processes are opponent").

It is probably true also that when people hear "opponent teams", they are thinking "team of opponents" more than "opposing teams", so the OP expression is actually an example of an attributive noun, rather than of an attributive adjective, so the other answer had it right.


When they fight against other opponent teams

As @Jack_O'Flaherty says, this is perfectly fine, and there's no issue with opponent teams. It's just incomplete because of the when.

When you use a noun as an adjective like this, these are called attributive nouns.

Basically, attributive nouns are a shortcut for saying:

  • X that/which is (a/an/the) Y

  • X which is used to obtain/facilitate/provide/do/complete Y

  • a Y that is dedicated to X or special because of X

opponent teams = teams that are opponents

apple tree = tree that provides apples

stirring spoon = spoon dedicated for stirring (as opposed to other function)

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