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I noticed there are many 形容詞{けいようし} (i-adjectives) that end in 〜ない, where the な is not part of the kanji, and doesn't seem to have the meaning 無い.


  • 危{あぶ}ない means "dangerous", while 危 means "danger"
  • 少{すく}ない means "few"/"scarce", while 少 means "few"/"little"
  • 切{せつ}ない means "heartrending"/"trying", while 切 means "earnest"/"ardent"

(For contrast, examples where it's clearly 無い: 心ない, 情けない, 力ない.)

I wonder where exactly this ない is coming from. It is not a classical Japanese ending to my knowledge (like 〜しい).

I speculate that it could be an alternative shortening of the classical Japanese copula 〜なり, but this is odd to me because I suspect the usual shortening of 〜な would be used if this were the case (as we see in 形容動詞{けいようどうし} (na-adjectives)).

Does anyone know the etymology of these words and/or the meaning of this 〜ない?

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危ない切ない –  snailboat Jan 24 '13 at 1:09
The -nai suffix is defined here:… –  Dono Jan 24 '13 at 1:14

1 Answer 1

up vote 9 down vote accepted

Thanks to snailplane's and Dono's links, it seems that the answer is fairly established:





Namely, 〜ない is also a suffix that attaches onto words describing state or quality, turns them into a 形容詞, and emphasizes them.

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Though if someone knows the etymology of 〜ない itself, that'd be pretty interesting to hear :). –  Darius Jahandarie Jan 24 '13 at 4:10
I don't know it well enough to post an answer, but Frellesvig brings up the possibility that ぬ was originally a copula that got converted into an auxiliary, possibly meaning "to be in a given state". See and somewhat before / after for a chat mostly between snailboat and me about this ぬ. If one assumes that the 未然形 was a real thing, ぬ > な(未然形) + ふ(反復・継続の助動詞) forms the なう verb ending, as in おこなう etc. This adjectival suffix なし has a somewhat similar meaning, and might have a similar derivation. ぬ might also be the root of なる. –  Eiríkr Útlendi Jun 6 '14 at 23:56
Nice, I didn't think of that connection! –  Darius Jahandarie Jun 7 '14 at 14:30

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