As we know, there is a class of adjectives that end in 〜らか: 滑【なめ】らか, 明【あき】らか, 清【きよ】らか, 安【やす】らか, etc.

やわらか (柔らか or 軟らか) is also in this class of adjectives. However, it can also be written as the イ-adjective やわらかい. So when and how did this adjective pick up an い to become a separate イ-adjective?

Can this be done arbitrarily with any of the 〜らか class adjectives? Like 滑【なめ】らかい, 明【あき】らかい, 清【きよ】らかい, 安【やす】らかい. My gut feeling is that it cannot, but only because those forms sound strange to me. If it cannot arbitrarily be done, are there any other 〜らか class adjectives that can take on the extra い?

  • 1
    やわらか does not work as a na-adjective. It is only i-adjective.
    – user458
    Commented Jul 3, 2012 at 15:18
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    Related: Unifying concept for noun-adjectives of the pattern Xかな
    – Flaw
    Commented Jul 3, 2012 at 16:08
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    We can say やわらかな. dictionary.goo.ne.jp/leaf/jn2/223492/m0u/…
    – Gradius
    Commented Jul 3, 2012 at 16:47
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    Wow I haven't noticed, how interesting... goo辞書 says やわらかな is 「[形動]」, and it says やわらかい is「[形]」,「形容動詞「やわらか」の形容詞化」. I can't think of any other ~~らか words that can be i-adjectives... Maybe やわらか(い) is a very unique word...?
    – user1016
    Commented Jul 3, 2012 at 17:09
  • 1
    Interesting. やわらかい is the only adjective ending with らかい listed in either Daijirin or Daijisen. Commented Jul 3, 2012 at 23:11

1 Answer 1


Firstly, as was noted in the comments (by Tsuyoshi Ito), that the same thing cannot be done with other adjectives ending in ~らか.

On the other hand, there exists a number of adjectives, which can function both as イ-adjective and as ナ-adjective, e.g.

大きい   大きな
小さい   小さな
真っ白い 真っ白な (etc.)
細かい   細かな
暖かい   暖かな
四角い   四角な (etc.)
柔らかい 柔らかな

(but, of course, やわらかい is the only one ending in ~らかい). An investigation of the differences here might deserve a separate question.

As for the difference in usage, I have talked to quite a few native speakers, who maintain that there is no substantial difference in meaning between やわらかい and やわらかな, which is only a handful of anecdotal evidence. On the other hand, here is an article (blog post?) about the difference between やわらかいお餅 and やわらかなお餅, where the author says something along the lines, that a やわらかなお餅 has a more gentle feel to it (he says 「やわらかな」のほうが落ち着く感じがする). Which, too, is at best anecdotal evidence.

One can only guess that maybe he means that やわらかい is a more objective statement about the physical properties of the お餅 (softness), whereas やわらかな suggests a subjective experience of softness, or rather gentleness.

But even if this is the case, not every Japanese person seems to perceive these subtleties in the same way...

P.S. I noticed that I haven't answered your question, regarding the history of the difference. I will delete my answer, if it isn't contributing anything to the problem of answering your question.

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