Dog eats dog sounds correct but it's not an adjective here. As soon as it becomes an adjective we remove s from eats, Why?

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    – user230
    Feb 9, 2020 at 14:15

1 Answer 1


Adjectives in English don't change to agree with the noun like they do in some other languages.

So if a noun is used as an adjective, it will be the singular form.

I have three cars.

I have three car decals.

It's easy to get mixed up because possessive nouns can be used attributively as adjectives and will keep the 's. So this sounds like an exception in speech but isn't.

I have the three cars' decals = I have the decals that belong to the three cars.

  • 5
    Yes but “eats“ has nothing to do with plural form.
    – user29952
    Feb 6, 2020 at 21:31
  • Yes it does. Eats is singular form, which has plenty to do with plural form. Feb 7, 2020 at 0:40
  • 1
    @JohnLawler - sure eats is singular as well as dog is. So why in “dog eat dog” the singular form “eats” is not used?
    – user29952
    Feb 7, 2020 at 10:18
  • First, asking "Why?" a particular language feature exists is a waste of time; we don't know why. Second, the form dog-eat-dog is not a sentence (which is where agreement comes in), but a fixed adjectival phrase with no internal syntax. Nobody was around taking notes when it was first used, so we don't know when, how, who, or why. Feb 7, 2020 at 16:29

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