Why is 一番おいしい grammatical?

The phrase 一番おいしい means "number one delicious" or "the most delicious". But 一番 is a noun and おいしい is an い-adjective, and as far as I know


isn't grammatical in Japanese, right? So is this a special case where 一番おいしい should just be thought of as a single い-adjective which means something like "number-one-most-delicious", rather than a noun merged with an い-adjective?

Understanding why 世界の一番おいしい isn't grammatical

From a Cure Dolly video on the usage of the で particle, it's stated that


is grammatically incorrect, since (in the narrator's own words):

Japanese words only modify words that come after them.

They can't modify words that come before them.

And because -no can't modify "oishii",

it can only modify "raamen", which is another noun,

and because "raamen" is on the wrong side of it, we can't actually use that.

But isn't 一番 a noun? So couldn't we parse this as


where (世界の一番) is modifying (おいしい)?

  • 2
    Did you look it up in a dictionary?
    – naruto
    Commented Sep 5, 2022 at 19:52
  • 1
    For your first question: 一番 can also be an adverb, as is the case here. For the second question, and here I only have an assumption, hence only a comment: I think the difference is fundamentally the same as between 学生は学校で遊んでいる and 学生は学校の遊んでいる. There is just something missing at the end of the latter.
    – Kaskade
    Commented Sep 5, 2022 at 19:54
  • 1
    naruto: I read your other post that shows how adverbs can modify adjectives, and after learning from @Kaskade (and also your post) that 一番 can be used adverbally, I understand how 一番おいしい makes sense as (adverb)(i-adjective). Moreover, (世界の一番) makes sense as a noun phrase, but since it's not an adverb, it can't modify (おいしい). So everything is clear to me now!
    – George
    Commented Sep 5, 2022 at 22:34


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