Monday, November 25, 2019

Irregular Verbs

Among verb types, irregular verbs are verbs whose conjugation is non-standard, and doesn't follow the usual conjugation rules that basically every other verb in the language follows.

The Japanese language is often said to have only two irregular verbs: suru する, "to do," and kuru 来る, "to come," which are also called "group 3 verbs," among the three groups of verbs in Japanese, the other two being godan verbs and ichidan verbs, whose conjugation would be regular.

Besides those, the words aru ある, nai ない, yoi よい, ii いい, and iku 行く also feature irregularities to watch out for. So I'm listing all of them here.


Japanese conjugation is extremely regular, unlike the English conjugation, which is a disgusting mess. Most verbs forms are created by using suffixes called jodoushi 助動詞. Observe:
  • kiru
    To wear. (non-past)
  • kita
    Wore. To have worn. Did wear. (past.)
  • kinai
    To not wear. (negative.)
  • kimasu
    To wear. (polite form.)

Above, the stem morpheme of the verb "to wear," ki~ 着~, remains the same across its different forms.

By contrast, the verb kuru 来る can have the vowel of its first syllable changed, giving multiple readings for the kanji 来. For example, the past form would be kita 来た, which starts with ki き, instead of ku く.



For reference, the conjugation of the irregular verb kuru 来る:
  • kuru 来る(る)
    To come. (non-past.)
    • Here, 来 is read ku く.
  • kita 来た(た)
    Came. To have come. Did come. (past.)
    • Here, 来 is read ki き.
  • konai 来ない(ない)
    To not come. (negative.)
    • Here, 来 is read ko こ.
  • kimasu 来ます(ます)
    To come. (polite form.)
  • kite 来て(て)
    To come and. (te-form.)
  • koi 来い(い)
    Come! (imperative form.)
  • koyou 来よう(よう)
    Let's come. (volitional form.)
  • korareru 来られる(られる)
    To be able to come. (potential form, and passive form, too.)
  • koreru 来れる(れる)
    To be able to come. (potential form, see: ら抜き言葉.)
  • kosaseru 来させる(させる)
    To make come. (causative form.)

Although the stem of the irregular verb is irregular, the suffixes remain regular. For example, the negative past form is konakatta 来なかった, "didn't come," and the polite past form is kimashita 来ました, "came." Just as you'd expect in any other verb.

Also, it's not really fair to say that the stem is irregular, since the k~ consonant stayed the same through all conjugations.

It's more appropriate to say that kuru is a sandan 三段, "three-column," verb, since its first syllable ranges across three vowels: ku-ki-ko くきこ.

The technical term would be ka-gyou henkaku katsuyou カ行変格活用, "ka-row irregular conjugation."


For reference, the conjugation of the verb suru する, too:
  • suru
    To do.
  • shita
  • shinai ない
    Doesn't do.
  • shimasu ます
    To do. (polite form.)
  • shite
    To do and. (te-form.)
  • shiro
    Do [it]! (imperative form.)
  • shiyou よう
    Let's do. (volitional form.)
  • dekiru できる
    To be able to do. (potential form.)
  • sareru れる
    To be done. (passive form.)
  • saseru せる
    To make do. (causative form.)

There are a few things worth noting about.

First, the irregular verb suru する and the irregular verb kuru 来る aren't even regular between themselves.

For example, the negative form of kuru 来る is konai ない, the stem syllable changes to the ~o vowel, but for suru する it's shinai ない, which ends in the ~i vowel. So they're two completely separate irregular verbs.

Second, you may have noticed that for some ungodly reason the word dekiru できる is written where the potential form of suru する was supposed to go. Surely, ,this must be a typo, right? Because dekiru できる has literally nothing to do with suru する.

This isn't a typo.
  • ryouri wo suru
    To do the cooking.
  • ryouri suru
    To cook.
  • ryouri wo dekiru
    To be able to do the cooking.
  • ryouri dekiru
    To be able to cook.
    Can cook.

The verb suru する is so irregular that its potential form is literally a whole different verb. I mean, seriously, dekiru 出来る by itself means, among other things, "to be made of."
  • karada wa tsurugi de dekite-iru
    [My] body is made of swords.

More literally, dekiru できる means "to realize," "to accomplish," "to finish (making)" something. If you can realize the act of cooking, it means you're able to cook.

Again, derived forms are regular. The past potential form of suru する is the past form of dekiru できる, in other words: ryouri dekita 料理できた, "was able to cook."

Beware: the verb suru する has dozens of different uses. In all of them, dekiru できる is the potential form.
  • mono ni suru
    To make it one's possession.
    [I] will make [it] mine.
  • mono ni dekiru
    To be able to mono ni suru.
    To be able to make it one's possession.
  • jiyuu wo te ni suru
    To put freedom in one's hand. (literally.)
    To acquire freedom.
    To obtain freedom.
  • jiyuu wo te ni dekiru
    To be able to obtain freedom.

By the way, if the potential form was regular, it would be the mizenkei form, se~, plus ~rareru, so serareru せられる. In fact, this form was once used in Japanese:
  • ai suru
    To love.
  • ai serareru
    To be able to love.

Nowadays, people don't say this. They say aiseru 愛せる, as if aisu 愛す were a godan verb.

Like with kuru, there's a technical term for the suru verb conjugation: sa-gyou henkaku katsuyou サ行変格活用, "sa-row irregular conjugation.".

This would also apply to ~zuru ~ずる verbs, which are simply suru with rendaku 連濁.
  • meizuru (mei suru)
    To order.
  • meijita (mei shita)


The verb aru ある, "to exist," is generally regular, except for one thing: its negative form is nai ない, "nonexistent." This only happens with the plain negative form. The polite negative form is arimasen ありません, as you'd expect to derive from the polite form arimasu あります.
  • kibou ga aru 希望がある
    kibou ga arimasu 希望があります
    Hope exists.
    There is hope.
  • kibou ga nai 希望がない
    kibou ga arimasen 希望がありません
    Hope is nonexistent. Hope doesn't exist.
    There is no hope.

Now, you may be wondering how does it make sense that the negative form of a verb is an i-adjective. Well, technically, the negative form of every verb in Japanese is a kind of an i-adjective, since they all end in nai ない anyway, so don't worry about it.

Once again, we have a verb that's used in a bunch of extremely weird ways, which is irregular on top of it. To begin with, it can be used to talk about possessions instead:
  • okane ge aru
    Money exists [in possession].
    To have money.
  • okane ga nai
    To not have money.

Such sentences, which refer to the existence or non-existence of something about someone, are a kind of double-subject construction. At first glance they look pretty normal, except that some of them are extremely complicated by themselves:
  • watashi niwa kankei aru
    There's a relationship to me.
    That has to do with me.
  • watashi niwa kankei nai
    That has nothing to do with me.
  • watashi wa {manga wo yonda} koto ga aru
    I have the experience [that is] {to read manga}.
    I've read manga before.
  • watashi wa {manga wo yonda} koto ga nai
    I don't have the experience [that is] {to read manga}.
    I've never read manga before.

The irregularity also happens when aru ある is used as a hojo-doushi 補助動詞:
  • kaite-aru
    To have been written.
  • kaite-nai
    To not have been written.
  • neko de aru 猫である
    neko de arimasu 猫であります
    [It] is a cat.
  • neko de wa aru 猫ではある
    neko de wa arimasu 猫ではあります
    (same meaning as above. See: wa は particle.)
  • neko de nai 猫でない
    neko de arimasen 猫でありません
    [It] is not a cat.
  • neko de wa nai 猫ではない
    neko de wa arimasen 猫ではありません
    (same meaning as above.)
  • neko janai 猫じゃない
    neko ja arimasen 猫じゃありません
    (same meaning as above, this is a contraction.)
  • kawaiku aru 可愛くある
    kawaiku arimasu 可愛くあります
    [It] is cute.
  • kawaiku nai 可愛くない
    kawaiku arimasen 可愛くありません
    [It] is not cute.


The i-adjective nai 無い is kind of irregular. That's only because, when using the suffix ~sou ~そう with it, the suffix is attached to its sa-form instead of the stem.

For example, while a normal adjective would look like this:
  • kore ga oishii
    This is delicious.
  • kore no oishi-sa
    The deliciousness of this.
  • kore ga oishi-sou da
    This seems delicious.

The nai 無い adjective looks like this:
  • kare wa okane ga nai
    Money is nonexistent is true about him.
    His money doesn't exist.
    He doesn't have money.
  • kare no okane no na-sa
    The nonexistentialness of his money.
    His lack of money.
  • kare wa okane ga na-sa-sou da
    He doesn't seem to have money.

The same applies to nai 無い as a hojo-keiyoushi 補助形容詞.
  • oishiku-na-sa-sou da
    [It] doesn't seem delicious.

However, when nai ない is a jodoushi 助動詞, the sa さ isn't necessary.
  • ame ga furanai
    Rain doesn't rain.
    It doesn't rain.
  • ame ga furana-sou da
    It seems rain doesn't rain.
    It seems it won't rain.


The verb iku 行く conjugates differently from other godan verbs ending in ~ku ~く. The past form ends in tta, and the te-form ends in tte. Observe:
  • kiku
    To heard.
  • kiita
  • kiite
    Hear [me]. (imperative.)
  • iku
    To go.
  • itta
  • itte
    Go. (imperative.)

Past form conjugation of godan verbs. 殺す, 殺した, 書く, 書いた, 泳ぐ, 泳いだ, 遊ぶ, 遊んだ, 死ぬ, 死んだ, 読む, 読んだ, 切る, 切った, 買う, 買った, 勝つ, 勝った, 行く, 行った. The くぐ endings are affected by イ音便. くぐぬむ are affected by 連声濁. ぶぬむ are affected by 撥音便. るうつ, and the verb 行く are affected by 促音便.


The i-adjective ii いい is the most irregular adjective in the whole Japanese language. Observe:
  • ii
  • yokatta
    Was good.
  • yokunai
    Is not good.
  • yoku
    Well [done].
  • yokattara
    If were good.
  • yokereba
    If be good.
  • yokarou
    Very well.

As you can see above, every one of its inflections is irregular.

In fact, it's actually the opposite: the actual adjective is yoi よい, which means the same thing as ii いい, "good," but in its predicative form and attributive form, the adjective ii いい is preferred over yoi よい.

The real past form of ii いい would be ikatta いかった, and its negative would be ikunai いくない.
いい. It seems that, in some regions of Japan, such words are actually used. In most of Japan, however, yokatta, yokunai, are used instead.[ 形容詞の「よい」と「いい」はどう違う?-, accessed 2019-11-02]

This is particularly important since ii いい has some weird functions, like:
  • tabete ii?
    Eating, good?
    Is it alright to eat it?
    Can I eat it?
  • yokunai
    Not good.
    It's not alright.
    No, you can't.


Like the nai 無い adjective, yoi 良い also gets the ~sou ~そう added to its sa-form instead of its stem.
  • kimochi-ii
  • kimochi-yo-sa-sou da
    It looks like it feels good.
    It looks like it's pleasant.


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  1. This article is an absolute godsend, well written, clear, funny and extensive, with simple to the point examples. THANK YOU SO MUCH!!

  2. This is more than useful. Very valuable as a reference for a beginner student like myself. Thank you and I hope you'll have more resources like this in the future.