"It seems there is none" is なさそう, which escapes the usual rule for 形容詞 (イ-adjectives), which says "drop the い and add そう".

Is there a historical explanation for this exception? And does it have anything to do with なさいません?

  • 2
    Likewise よい -> よさそう. What do you mean by "how come"? That's just the way it is.
    – Billy
    Commented Sep 12, 2012 at 2:05
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    Well, you can answer any question with "that's just the way it is"... I am wondering if there is an explanation of why it is なさそう, rather than なそう. One possible explanation would be that ない is too short by itself and なそう sounds odd, so that さ was inserted in order to make it better sounding (just like for よさそう). Another explanation might involve the changes of the word ない and its relation with なさいません... I don't know if there exists a reasonable explanation, but that doesn't mean there is none.
    – Earthliŋ
    Commented Sep 12, 2012 at 2:16
  • Well, regardless of whether that was historically the case, Japanese people now say なさそう rather than なそう because the former is correct and the latter isn't. Historically there's probably a good reason (maybe along the lines of: "な" and "よ" are unstressed and short so will get lost?), but you quoted a grammatical rule of current modern Japanese, so I was confused as to what your question is. In modern Japanese, that is just the way it is.
    – Billy
    Commented Sep 12, 2012 at 2:25
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    @Billy I have several friends in Sendai who say なそう.
    – Dono
    Commented Sep 12, 2012 at 2:26
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    @dono: Ha? I lived several years there and never heard it. I'll poll around!
    – Axioplase
    Commented Sep 12, 2012 at 3:47

2 Answers 2


Your "usual rule" is incomplete. It should be:

  1. drop -i
  2. if resulting is a single mora in length, add -sa
  3. add -sou.

Hence, nai:

  1. na
  2. na + sa
  3. na + sa + sou --> nasasou.


  1. atu
  2. (not applicable)
  3. atu + sou --> atusou.
  • 1
    There are more. The number of combinations are few, so it should be easy to verify. Going from the top, ui (憂い) --> usasou. Check Google for usage.
    – Dono
    Commented Sep 12, 2012 at 2:24
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    Might be worth pointing out that this occurs for negative adjectives too, e.g. 暑くなさそう, because 暑く and なさそう are parsed separately. Also compounds: かっこ(う)よさそう.
    – Billy
    Commented Sep 12, 2012 at 2:28
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    @istrasci Jesse has already responded, but I would like to follow up. This is one case where knowing the historical spelling would help avoid the confusion. Historically, urei was 憂ひ (and 憂へ before that). Hence urepi > ureɸi > urewi > urei. As such, the final -i cannot be adjectival suffix -i. This is a noun. My comment was about the adjective ui. For completeness, note that the adjectival -i derives from -ki with the -k- dropping out. This -ki form is the attributive form of -si.
    – Dono
    Commented Sep 12, 2012 at 6:55
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    So do you say 濃さそう or 濃そう? I believe the last form is the more common, contradicting your rule.
    – dainichi
    Commented Sep 12, 2012 at 23:11
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    @dainichi: Thanks for finding another example. I'm also in favour of 濃そう.
    – Earthliŋ
    Commented Sep 13, 2012 at 1:55

Well, in first place there are possible confusions depending you are referring to ない as a [助動詞]{じょどうし} or 無い as a [形容詞]{けいようし}.

In the case of "It seems there is none", なさそう will be 無い adjective [連用形]{れんようけい} + そうだ [助動詞]{じょどうし}。

It seems that when そうだ was first introduced at Muromachi period, なそう was used but as な is only one syllable, さ was added through time.

It has nothing to do with なさいません which is the negative form of [為]{な}さる verb.

For information, in the case of ない as a [助動詞]{じょどうし}, なそうだ is used:


But recently, さ is sometimes added:


  • Thanks, I like the idea of thinking of ない as auxiliary rather than 形容詞, but I don't really like calling it a 助動詞. Do you have any reference for ない being called a 助動詞?
    – Earthliŋ
    Commented Nov 23, 2012 at 12:24
  • Reference 未然形 - 打消. 無い as a 形容詞 and ない as 助動詞 are just homonyms (and have a close meaning to confuse the things even more).
    – Eric
    Commented Nov 23, 2012 at 12:34

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