Good afternoon all,

From what I understand, special "suru" verbs only have one potential form which is formed using the syntax:

[verb-stem] + [せる]

For example, 愛す・愛する → 愛せる and 訳す・訳する → 訳せる.

However, A Dictionary of Advanced Japanese Grammar claims that "熱する (ねっする)" and "察する (さっする)" conjugates in the same way as "する". Snippet:

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By that claim, it seems to mean that the potential form of "熱する" would be "熱できる (uh, ねっできる?)" and the potential form of "訳する" would be "訳できる".

WWWJDIC also has a chart which shows that the potential form of "訳する" is "訳しえる" and/or "訳しうる" (link).

So now we have these potential forms:

  1. [verb-stem] + [せる] (e.g. 愛せる, 訳せる, 熱せる, 察せる)

  2. [verb-stem] + [しえる] (e.g. 愛しえる, 訳しえる, 熱しえる, 察しえる)

  3. [verb-stem] + [しうる] (e.g. 愛しうる, 訳しうる, 熱しうる, 察しうる)

  4. [verb-stem] + [できる] (e.g. 愛できる, 訳できる, 熱できる, 察できる)

Are all of these 4 conjugations grammatically valid potential forms of special "suru" verbs?

  • 1
    I believe the 4th is not valid ...
    – fefe
    Commented Mar 27, 2012 at 4:02
  • 1
    +1 Great question!
    – istrasci
    Commented Mar 27, 2012 at 14:12
  • +1, I was just about to post a duplicate of this. Commented Mar 14, 2016 at 2:12

2 Answers 2


As @fefe mentions, the 4th one is wrong for the examples you mention. I think your grammar book forgot about the potential.

I don't know the detailed etymology, but I guess somehow 愛する, 訳する, 熱する, 察する are more like "proper verbs" (although they inherit most of the irregularities of する), whereas 勉強する etc. are still more like a compound: noun+する, thereby inheriting also the suppleted potential of する, できる.

  • 1
    Right... we can only use できる as 愛することができる, 訳すことができる, 熱することができる, 察することができる.
    – user1016
    Commented Mar 27, 2012 at 8:44
  • 1
    @Chocolate, dainichi, btw are the しえる and しうる forms considered literary? For example, will "愛しえる" / "愛しうる" sound "weird" or are they in common use?
    – Pacerier
    Commented Mar 27, 2012 at 9:40
  • 1
    @Pacerier-san, I think 愛せる/訳せる, 愛しえる/訳しえる and 愛しうる/訳しうる would be fine, but I rarely use the ~~し"え"る form. I often use the negative form 愛し"え"ない/訳し"え"ない though (and 愛せない/訳せない too. Because we don't have the form 愛しうない/訳しうない). 愛せる/訳せる sound most casual and 愛しうる/訳しうる sound most literary to me. As for 察せる/察しえる/察しうる・・・ I think this word is rather difficult to treat because: oshiete.goo.ne.jp/qa/3126695.html
    – user1016
    Commented Mar 28, 2012 at 14:53
  • @Chocolate Thanks for the reply =D Btw just to clarify, do you mean that "愛しうる" has no negative form? Does "愛しうらない" work?
    – Pacerier
    Commented Mar 29, 2012 at 22:40
  • 3
    @Pacerier, 愛しうらない doesn't work. うる is really a fossilized 連体形 of the classical Japanese (auxiliary) 下二段活用 verb う, which in negative would be えぬ・えず. In modern Japanese 下二段活用 verbs turned into 下一段活用 verbs, i.e. える with negative えない. In short, える and うる are really the same verb, the latter is just a fossilized archaic conjugation. Negative is the same for both.
    – dainichi
    Commented Mar 30, 2012 at 2:08

In order here.

1 These are valid words, but not valid する verb forms. That is to say the verbs in these cases are 訳す, 愛す, etc. In the case of some of these the す verb is much more commonly used than the する verb and can probably be considered the "correcter" version of the verb.

2 + 3 These are valid and in fact the exact same thing. They are both ~得る when written in kanji. An example word using this grammar form would be ありえない. For the exact difference between this and the common modern potential forms consult your grammar book.

4 できる is the correct potential form for most する verbs in modern Japanese. However it is not valid in the case of す verbs. 達できる, 熱できる, etc are wrong.

If you are in doubt about the correct potential form of one of these verbs use ~うる when writing since both する and す verbs result in the same thing in these cases. When speaking use ことができる if you want to be safe.

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