How do these two verbs differ?

3 Answers 3


More or less like "I love you" and "I love thee" differ. 愛す is an older form with basically the same meaning. Same with other す/する pairs like 略す/略する、座す/座する etc.

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    Ok, I see. However, I was told my a native speaker that you can say, for example 愛さないこと but not 愛しないこと and that you wont say 愛すこと but will say 愛すること。What's the deal with that?
    – Tyler H
    Commented Apr 25, 2017 at 21:18
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    Why not *愛すこと: long story, but older Japanese had more conjugations. You know how 話す looks the same in "人が話す" and "話す人"? In Classical Japanese, the second was different: 話す者. So 話す had a 話する- inflection when modifying nouns. す also had a する- inflection when modifying nouns—in fact this is the source of modern する! So you can't say *愛すこと because the old-style inflection of a す verb before a noun is する-。 Commented Apr 25, 2017 at 21:32
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    Why not 愛しないこと: I don't know! It should be grammatical for modern 愛する. The only thing I can think of is that the earlier 愛さない⁠- was well-established enough to block the new form 愛しない⁠-—even though 愛す itself is now less common. I note, however, that I can find quite a few seemingly valid examples of 愛しないこと in Google Books and elsewhere in the wild, even if that would raise eyebrows among native speakers. Commented Apr 25, 2017 at 21:45

Conjugations of [single-on'yomi-kanji] + する verbs are unstable due to the lingering influence from Classical Japanese. In short, there are two variants (五段/consonant-stem and サ変/suru-stem) of the same verb always coexist.

 愛す       愛する
 愛さない   愛しない
 愛します = 愛します
 愛した   = 愛した
 愛せば     愛すれば
 愛せ       (愛しろ; rare)
 愛そう     愛しよう
 愛せる     (no equivalent)

(As for imperative, the Classical conjugation 愛せよ is still wide in use as a bookish expression, but not in everyday language.)

Except those I put in brackets, both series of forms are expected to appear in the real life, with varied probability. This is applied to all verbs of the same kind, including 適す(る), 略す(る), 制す(る), 有す(る) etc. Moreover, the probability which series of conjugation (or even, whose particular form) is used also differs among verbs; for example, I usually hear the 愛す column used more for 愛, but 制する for 制.

Note that some verbs apparently have similar forms actually don't belong this type. For example, 楽する looks like another bird of a feather, but it's actually a colloquial form of 楽をする which is not one solid word, so it doesn't have *楽す version. The accents are different: らく{LH}する{LH} vs あいする{LHHL}.

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    Late comment but the part about accent is quite interesting, thanks for pointing that! Commented Jun 20, 2017 at 9:30
  • I believe the right column should have 愛せよ (imperative) and 愛せられる (potential) Commented Dec 5, 2020 at 5:07
  • @JerryFielder Thank you for the suggestion. Though I doubt 愛せよ is a "modern" conjugation, it is certainly used in modern context, so I'll find a way to incorporate it in my answer. 愛せられる is theoretically potential as well, but I've never heard such a usage (only as passive). Commented Dec 5, 2020 at 13:13

Other than the answer by Ieboiko, sometimes 「愛する」and 「愛す」 are not interchangeable.

When A loves B you can say "A is a person who loves B", and also "B is a person whom A loves". If you say them in Japanese with using the word 「愛す」, you can say as:

  • AはBを愛す人です。or Bを愛す人はAです。 - A is a person who loves B.
  • BはAが愛す人です。- B is a person whom A loves.

But, in case of using the word 「愛する」, the situation differs.
You can say

「BはAが愛する人」 which means "B is a person whom A loves",

but you can't say

「AはBを愛する人」 which would have meant "A is a person who loves B".

I don't know why, but at least I can say that 「愛す」 and 「愛する」are not always interchangeable.

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    ですが「を愛する人」で検索する google.co.jp/search?q="を愛する人" といっぱい出てくるのですが… Commented Apr 26, 2017 at 13:09
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    @broccli forest I don't think the expression "を愛する人" is natural as Japanese.
    – user20624
    Commented Apr 26, 2017 at 13:19
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    @broccoli forest I know the famous phrase "春を愛する人" in a famous lyrics, but in this phrase "春" is not a person. I don't know why I could accept the phrase "something を愛する人", but I couldn't accept the phrase "somebody を愛する人".
    – user20624
    Commented Apr 26, 2017 at 13:55

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