There are at the very least several i-adjectives can be used as na-adjectives by dropping the final い and adding な in its place. The most common examples of this, as far as I am aware, are 大きい and 小さい, which become 大きな and 小さな, respectively. For quite a while, these were the only examples I was aware of, and so I was able to accept them as just "an exception to the rule." However, as I was just watching an anime, I came across おかしな, which I'd not heard previously.

Update. Ignacio Vazquez-Abrams pointed out in a comment that 暖かい can also be used in this way (i.e. 暖かな). I guess that means I have to take back my claim that only the three above can be used as na-adjectives. I will continue to search.

Update 3. It's been quite a while since I originally asked this question, and it appears that in the interim, dainichi has found two more instances of where this is possible. Specifically, やわらかい → やわらかな and 細【こま】かい → 細【こま】かな. So maybe there are some criteria to determine which adjectives can be used in this way, after all.

In the interest of getting a definitive answer, I've decided to offer a bounty on this question. The best answer will address the following points fully, with sources cited where possible (academic research or dictionary entries / grammar resources are preferred):

  1. It has been suggested that the ~な usage adds a higher level of subjectivity; is confirmation of this assertion available?

  2. We have determined a list currently of six adjectives which can be used in this way, outlined below. Are there any other i-adjectives which can be used as na-adjectives in this manner?

  3. Is there a system or set of criteria which can be used to identify adjectives which can be used in this way?

    a. If YES, what is that system or set of criteria?

    b. If NO, why can this set of adjectives be used in this way?

If you would like the question to be clarified further, please leave a comment and I will be more than willing to do so if possible.

Currently Identified i→na Adjectives

  • 大【おお】きい ⇒ 大【おお】きな
  • 小【ちい】さい ⇒ 小【ちい】さな
  • おかしい ⇒ おかしな
  • 暖【あたた】かい ⇒ 暖【あたた】かな
  • やわらかい ⇒ やわらかな
  • 細【こま】かい ⇒ 細【こま】かな

Related question: Why does Japanese have two kinds of adjectives? (-i adjectives and -na adjectives)

  • 5
    And 「暖かな」/「暖かい」. Commented Jul 12, 2011 at 9:16
  • In anime etc I think using the form also can indicate a greater level of "cuteness" in the case of 小さな/ちっちゃな vs 小さい/ちっちゃい. (e.g. as in ちっちゃな雪使いシュガー)
    – user797
    Commented Oct 29, 2011 at 5:53
  • There's also やわらかな・やわらかい and 細かな・細かい
    – dainichi
    Commented Jan 21, 2012 at 18:47
  • 1
    There is also 四角い・四角な and 真っ白い・真っ白な (and also 真っ黒い・真っ黒な). I tried to summarize some of my findings about the い-adj. vs. な-adj. in my answer to (my) question japanese.stackexchange.com/questions/6675. In particular, the な-alternative of the い-adj. is not really an adjective, but a 連体詞.
    – Earthliŋ
    Commented Nov 27, 2012 at 4:04
  • 3
    – user1478
    Commented Nov 27, 2012 at 8:54

6 Answers 6


Some Preliminaries

I first think it's necessary to clear up something that has been confusing me from the start: we are actually talking about two different classes of words. The first is the original set of three: 大【おお】きい、小【ちい】さい、可笑【おか】しい. The rest of the words we're talking about are all different than these three.

The Special Three... And All The Rest

Why are these three special? To answer that, we have to take a look at the grammar of Japanese adjectival forms, what we commonly know as i-adjectives (形容詞【けいようし】) and na-adjectives (形容動詞【けいようどうし】). It's a bit more complicated than that in reality, but those are the biggest two sets and the most relevant to our discussion.

One thing that makes these three words special is that they are i-adjectives with a na-adjective form. That is also true of the rest of our examples, which I will come back to shortly. What is extra special about these three words, and no others1 is that they are incomplete na-adjectives that can only be used to modify a noun; they are like, broken.

All the other words that have been suggested, and indeed all those that could be suggested, have fully-fledged na-adjective forms that can be used in any situation a normal na-adjective can.

The Nitty Gritty & Some Examples

Conjugable words in Japanese (用言【ようげん】, essentially verbs and adjectives) have six different stem forms (活用形【かつようけい】). I'm going to talk about three of them, because they're pretty common with both types of adjective: continuative form (連用形【れんようけい】), terminal form (終止形【しゅうしけい】), and attributive form (連体形【れんたいけい】).

With normal adjectives, we can use all of these forms:

  • ○ ゲームを安【やす】く買【か】えるお店【みせ】 (continuative form)
  • ○ ゲームが安【やす】い (terminal form)
  • 安【やす】いゲーム (attributive form)

That's true of na-adjectives as well:

  • 幸【しあわ】せでいられる人【ひと】 (continuative form)
  • 静【しず】かに読【よ】む (continuative form)
  • ○ その人【ひと】が幸【しあわ】せだ (terminal form)
  • 幸【しあわ】せな人 (attributive form)

There are a couple other ways to make some of these forms, but these are the prototypical examples. Now, here's the deal: the three words in the "special" class I discussed above (大【おお】きい、小【ちい】さい、可笑【おか】しい) can only be used in the attributive form. So we end up with something like this:

  • × 可笑【おか】しで描【か】く (bad, continuative form)
  • × 絵【え】が可笑【おか】しだ (bad, terminal form)
  • 可笑【おか】しな絵【え】 (good, attributive form)

This pattern is true for all three of these adjectives, and not for any other i-adjective. The difference is that with any of the other examples, all of the other stem forms are possible, for example:

  • 柔【やわ】らかに焼【や】く
  • ○ パンが柔【やわ】らかだ
  • 柔【やわ】らかなパン


So, let me get back to the questions at hand.

Does the ~な usage really add a higher level of subjectivity?

Honestly, I don't know. Most of my research was on the usage and classification, not actually on the resulting meanings. It was suggested that the [n] sound in Japanese tends to add a softer feeling to words2, and that may influence the meaning here.

Are there any other i-adjectives which can be used as na-adjectives in this manner?

Yes and no... other than our Special Three, there are no i-adjectives that can be used as na-adjectives in only a limited capacity. There are, however, a number of other i-adjectives that also function as na-adjectives, for example, those suggested in a comment by @user1205935 (and I imagine there are any number more):

  • 四角【しかく】い ⇒ 四角【しかく】な
  • 真【ま】っ白【しろ】い ⇒ 真【ま】っ白【しろ】な
  • 真【ま】っ黒【くろ】い ⇒ 真【ま】っ黒【くろ】な

Is there a system or set of criteria which can be used to identify adjectives which can be used in this way?

Since I've divided the words up into two groups, this warrants two answers. A research paper I found1 suggests that words which are both i-adjectives and fully-functional na-adjectives generally fall into one of several categories, including color, [edit this].

On the other hand, our Special Three seem to be unique, so there isn't much of a system, per se. And finally...

What makes the Special Three special?

That's a difficult one. I have yet to find a satisfactory answer; I suspect that no one knows, exactly. There are a number of theories (for example, that explained in @Kafka Fuura's answer) but there isn't anything approaching a real consensus. Unfortunately, this one is probably going to remain a mystery for now.

Side Notes

Now, there is actually a class of words which encompasses our Special Three: attributive words (連体詞【れんたいし】). There are actually quite a few of these words that can only be used in front of a noun, and they fall into several smaller subcategories: attributives ending in ~の (e.g. あの、この、その); attributives ending in ~る (e.g. いわゆる); and attributives ending in ~た (e.g. たいした).

Of course, our Special Three (the only attributives ending in ~な) function a bit differently than all of the others.

So for that reason, I don't much care for the classification of "attributive words" -- it combines a lot of words which work in very different ways together into one category, ignoring the underlying nuances. And the Special Three, which are even more special.

But you should probably know that category does exist. Technically.


1 Backhouse, A. E. (1984). Have all the adjectives gone?. Lingua, 62(3), 169-186.
2 Makino, S., & Tsutsui, M. (1989). A dictionary of basic Japanese grammar: Nihongo kihon bunpō jiten (Vol. 1). Japan Times (Tokyo, Japan).

Note: I can provide a copy of the Backhouse article if you're interested in reading it.

  • It is worth noting (I probably should have mentioned it too) that the special three (and 同じ) are not fully considered 連体詞 because all other 連体詞 cannot exist in the predicate of a sentence (according to 三省堂 大辞林). Commented Nov 28, 2012 at 1:59
  • 4
    One of the things that interests me most is "when" these special three (or four) came about? Did they exist as 大きなる etc or was it only after なる became shorted to な? Commented Nov 28, 2012 at 2:01
  • 1
    "they are like, broken." I believe the proper term is "defective".
    – user1478
    Commented Nov 28, 2012 at 6:20

This is what I have concluded:

[大き・な, 小さ・な, [可笑]{おか}し・な]

Form a class of "[連体詞]{れんたいし}" ("adnominals") that are either な-adjectives that are either restricted to 連体形 ("modifying form") only or pseudo な-adjectives that only have a 連体形. However, because the restrictions of these three are not exactly the same as other 連体詞 (like for instance この/その/あの) they are often listed as な-adjectives, usually with a note saying that their usage is limited.

All other 連体詞 are actually verbs/adjectives/nouns/phrases that follow classical grammar rules that have been restricted for modern use, or rather most aspects of their original forms have been deprecated. (いわゆる is a great example of this, as it is 言ふ conjugated with the Heian auxiliary verb ゆ).

As for addressing the other adjectives mentioned (and also 大きい/小さい):


If you trace them etymologically they are just two separate forms of adjectives that branched from the same source. Theoretically, there should be no difference between them, though they may naturally have gained some nuances. I've never heard of the "subjective" argument though.

Etymology chains for those curious:
 many of these motions are based on not 100% accepted theory








おお(n)→おお・し(adj)→おお・き(adj's 連体形)→おおき・し(adj)→おおき(n-adj)


ちす(v)→ちさ(n)→ちいさ(sound change)→ちいさ・し(adj)→ちいさ(n-adj)

While some of the end bits of that probably occurred in a 1→2 fashion, some of them may have evolved concurrently, so it would be hard to make a set rule or assumption based on how the word was derived. However, if anything, it seems clear that all of the na-adjectives that have regular adjective counterparts that are not strange 連体詞 anomalies were na-adjectives before they were adjectives. I wouldn't say the reverse is valid right away because 小さな/小さい doesn't have any indication that 小さい came before 小さな, but 可笑し・な was clearly an しく adjective before they it was a (pseudo) な adjective.

That's my two cents.

If we could find any more examples of those sort of dual/form adjectives to give merit to the above assumption/theory that would be awesome, but I doubt it'd be enough to make it substantial.

  • I went ahead and removed 同じ from the my answer because it's too much of an oddball to be grouped with the other three. Commented Nov 28, 2012 at 2:05
  • I awarded the bounty here because your notes on the possible etymology of these words is very interesting. Thanks!
    – rintaun
    Commented Nov 30, 2012 at 17:00

Very interesting question as it is mixing a few different concepts.

  • い adjective 形容詞【けいようし】 (e.g.: 大きい、小さい)
  • だ adjective-verb 形容動詞【けいようどうし】 (e.g.: 便利だ、綺麗だ)
  • 〜な (大きな) 連体詞【れんたいし】 (e.g.: 大きな、小さな)

The main confusion comes from the fact that the adjective-verb 連体形【れんたいけい】 looks like a 連体詞【れんたいし】. Consider the following examples:

綺麗な指輪。 A beautiful ring
大きな丘。 A big hill

One could be easily tempted to say this is a similar grammatical construction, but it is not.
In the first sentence it is a adjective-verb (形容動詞) 連体形 form, and in the second sentence, it is a 連体詞.

One way to know if 大きな is a 形容動詞 or not is to try to conjugate it as a 形容動詞 would, eg: 大きだった, that should feel totally unnatural.

So the previous example conjugated will be:

綺麗だった指輪。 (still a 形容動詞)
大きかった丘。 (switched to a 形容詞)

A rule of thumb in this case is that any い adjective you see with a な ending is not used as an adjective-verb, but as a 連体詞 and thus cannot be conjugated in the same fashion of an adjective-verb.

連体詞 are a very unique grammatical structure, and even native speakers sometimes conceptually mix them with 形容詞 or 形容動詞。

A few links in case you want more information:


And finally, is there any difference in nuance or feeling when these are used as na-adjectives versus i-adjectives?

Short answer: Consensus is "using the な version makes the adjective more subjective".



As others have explained, most of these are pairs of ~い and ~な adjectives that both arose in parallel from single roots.

The oddballs are 大きな・小さな・可笑しな, which exist only as adnominals -- they must be followed by nouns, and cannot be used predicatively (at the end of a sentence) -- and which have no corresponding に adverbial forms.

However, one of these three is not quite as odd. 可笑【をか】し existed as the well-known terminal form of modern adjective 可笑【おか】しい, but it also existed as the noun 可笑【をか】し・可笑【をかし】. Definitions and quotes, excerpted from Shōgakukan's 国語大辞典 (emphasis, furigana, and dates added by me):

1 笑【わら】うべきこと。滑稽【こっけい】。戯【たわむ】れ。*史記抄【しきしょう】 (1477)‐一七「をかしをすれども道【みち】に合【あ】ふぞ」
2 猿楽【さるがく】、間【あい】狂言【きょうげん】などの滑稽【こっけい】な劇【げき】。また、それを演【えん】ずる人【ひと】。*看聞【かんもん】御記【ぎょき】‐永享四年 (1432) 一〇月一〇日「​拍子咲(ヲカシ)​などは男也」

This root is probably derived in turn from now-archaic verb 招【を】く as appears in the 古事記【こじき】 and the 万葉集【まんようしゅう】, and as suggested at Gogen-Allguide, from the sense of "something that causes one to draw near (because it's funny and interesting)". I believe the な conjugation derives from the noun form.


The method foreigners learn Japanese and Japanese learn Japanese is different. The concept of い形容詞 and な形容詞 doesn't exist to natives.

Native Grammar 形容詞

  • Your い Adjectives.
  • Ex: 大きいもの
  • Ends in い so follow your rules you know
  • Native Grammar 形容動詞

  • Your な Adjectives.
  • Ex: きれいな、きれいだ、きれいに
  • Has に、だ following
  • Native Grammar: 連体詞

  • Some are your な Adjectives. (some of your exceptions in your listing)
  • Ex: 大きな、この、あの、その
  • Never followed by に、だ(you never say 大きいだ)
  • Entire books are written on this subject alone, however, I recommend you either (a) continue how you're learning and learn the situational uses, or (b) spend several months studying Japanese from Japanese books themselves (requires advanced level). The terms I listed should help you further in your studies.

    I was fortunate to have both opportunities, the latter at a Japanese university. Japanese, like most modern languages, is a mess, really, so don't always worry so much about the logic behind it.

    • 3
      I get your point that there might not be a systematic or etymological pattern interesting or significant enough to merit a full-time inquiry, but I wouldn't say that it is just "a mess". You could be dismissing something big and important by proscribing it as just something arbitrary. If it is arbitrary, that doesn't necessarily mean it is inane, and it still might be worthwhile to approach it critically, even if just as an exercise. But I do get what you say so, ノートしました。
      – taylor
      Commented Nov 27, 2012 at 22:23
    • 3
      I agree on learning by Japanese terms, and I still think it's a shame that even university students rarely even cover/mention the base tenses (未然形、連用形、連体形、終止形、已然形、命令形) - but along exactly the same lines, learning what is the way it is because of a simply a sound change, or deeper meaning is essential to true understanding. One of my textbooks covers the phrase "いわんばかり" without explaining that it is a sound changed form of 言はむばかり - it even seemed to link it to a "negative" form. This made me very sad. Commented Nov 28, 2012 at 0:58

    You must log in to answer this question.

    Not the answer you're looking for? Browse other questions tagged .