The Bases of Japanese Verbs

Japanese has very long verb phrases. Things attach to verbs in various ways to produce phrases like 急がなければならない. Just to think, it can be way longer than this. This chain can easily go past six things in succession.

How is this all possible? Japanese is called an agglutinative language (膠着語 こうちゃくご). Agglutination is the concept of things attaching in chains. These chains have bases and endings interwoven like strands of DNA.

Many advanced students often complain about the terms “Ru Verbs” and “U Verbs”. However, they’re more correct than other names like “Class 1” and “Class 2”, which are arbitrary and contradictory to the traditional Japanese names.

From a traditional standpoint, there are 5 main classes of verbs in Modern Standard Japanese (標準語 =ひょうじゅんご).

  • 上一段活用動詞 (見る, 用いる, Etc.) Kami-ichidan Verbs       (roots end in i-)
  • 下一段活用動詞 (食べる, 求める, Etc.) Shimo-ichidan Verbs       (roots end in e-)
  • 五段活用動詞  (買う, 待つ, Etc.) Godan Verbs           (roots end in consonants)
  • サ変活用動詞 (する)   S-row Irregular Verbs           (root is s-)
  • カ変活用動詞    (来る)  K-row Irregular Verbs          (root is k-)

一段 verbs are collectively widely known as “Ru Verbs”. The prefixes 上- and 下- mean “upper” and “lower” respectively, and they refer to the vowels that end the roots of the verbs in their classes. So, the only difference between the roots of 見る and 食べる is that the former’s root ends in i- whereas the latter’s root ends in e-.

There are only two irregular verbs in Japanese now, but there used to be more. However, する is still not alone. In fact, ~ます, which makes sentences polite, conjugates the same way as it.

Despite there being minor differences in regards to the names of the classes, the main differences come from explaining how things happen after the root.

The view used at NihonShock involves a simplified 7 base system.

  • ~A: 動か、食べ、し(する)、こ(来る)
  • ~I: 動き、食べ、し、き
  • ~U: 動く、食べる、する、来る
  • ~E: 動け、食べれ、すれ、くれ
  • ~OU: 動こう、食べよう、しよう、来よう
  • ~TE: 動いて、食べて、して、きて
  • ~TA: 動いた、食べた、した、きた

This sufficiently accounts for most beginners’ needs in understanding how Japanese conjugates. However, for those hungry for minute details of grammar, you will eventually run into roadblocks with this method.

The Traditional Verb Forms

It’s now time to introduce the traditional base terminology used in Japanese grammar studies. Below are the Japanese names of them along with standard English translations of those names. If you don’t know some of the English words, don’t worry, this post will go over each of them in turn.

  • 未然形 みぜんけい Irrealis Form
  • 連用形 れんようけい Continuative Form
  • 終止形 しゅうしけい Predicative Form
  • 連体形 れんたいけい Attributive Form
  • 已然形 いぜんけい Realis Form
  • 命令形 めいれいけい Imperative Form

未然形: Negation and volitional action have something in common. They both represent things that haven’t occurred yet. You may or may not have the will to do something, but regardless, you still haven’t done it yet. Thus, the endings we associate those concepts in Japanese follow the 未然形.

So, in actuality, the endings ない, ぬ, ず, う, and よう follow the 未然形. This means that the “A” and “OU” bases are versions of the same thing. The “OU” base simply notes a sound change that occurred when the A ending base, Mizenkei, was paired with う.

行く → 行か- + -う → 行かう → 行こう

What about しよう and 来よう? They take ~よう. But, remember, they’re irregular. So, their bases look different. Other than that, they are like any other verb.

Note: The “OU Base” name in the simplified system could be more accurately described as the “O Base” given that the endings for the volitional are ~う and ~よう.

That’s not all. You also use the 未然形 to make passives and causatives. So, then, why is する not しれる or しせる respectively? The answer is that it has more than one 未然形. It actually has three. し → さ for these endings. So, you get される and させる. With old endings like ぬ and ず, you use せ. Thus, せず (=しない).

連用形: The 連用形 is the “I” base. It is the base for tense, conjunctive, and politeness items. This means you use it with ~た, ~て, ~ます, compound verb endings, and a whole lot more!

聞く + て → 聞いて  食べる + ます → 食べます.

Now, what about the “TE” and “TA” Bases? If 五段/U Verbs are have roots that end in consonants, why don’t you say 聞きて instead of 聞いて? Actually, the latter is a sound change of the former. The “k” is just dropped.

持ちてきたるか。 (Middle Japanese for: 持ってきたか)

None of the sound changes in 五段 verbs involve a different base. However, it is important to isolate the different sound changes. Thus, to make traditional grammar and the simplified base system more systematic, the “TE” and “TA” bases should be called sound changes rather than bases.

終止形・連体形: The “U” base corresponds to both the 終止形 and 連体形. However, from a grammatical standpoint, the two cannot be confused with each other. Very important structural properties of Japanese sentence structure are intertwined with them which this article won’t delve into. Nor will we get into how this is all done in English, as it is arguably even more complicated in English. The same goes for English in its own way.

已然形: The 已然形 is weird. Ever wondered why you get things like 見れば, 食べれば, and 泳げれば? Note that the latter is the ば-form for 泳げる, not 泳ぐ! If you’ve caught on that 見れ, 食べれ, and 泳げれ are 已然形, you’re ahead of the game. This base is rare and only used for a handful of endings. “Realis” means “realized”, which is why it’s used with endings like ~ど. However, ~ば makes a hypothetical. This is relatively new in Japanese. So, some Japanese grammarians call it the 仮定形 (the hypothetical form).

見れど (Although…see)   書けば (If…will write)

命令形: The 命令形 is neglected in the 7 simplified bases. This base is typically avoided because teachers don’t want students to make highly charged, rude commands to Japanese people. What it looks like is completely dependent on the class of the verb.

In summarizing this traditional approach to bases, the following chart shows the bases.

Class 未然形 連用形 終止形 連体形 已然形 命令形
上一段 い~ い~ いる いる~ いれ~ いろ・えよ
下一段 え~ え~ える える~ えれ~ えろ・えよ
五段 あ~・お~ い~ う~
サ変(する) し・さ・せ~ し~ する する~ すれ~ しろ・せよ・せい
カ変(くる) こ~ き~ くる くる~ くれ~ こい

Endings for 未然形: ~ない, ~ぬ, ~ん, ~ず, ~う, ~よう.
Endings for 連用形: ~た, ~て, ~ます, ~たら Etc.
Endings for 終止形: ~と, ~なら, ~べきだ, Final Particles like よ, ね, Etc.
Endings for 連体形: None. Precedes noun phrases.
Endings for 已然形: ~ば, ~ど
Endings for 命令形: All ancient.

Note: Remember the 未然形options for する and what they go to!

しれる・せれる → される・せられる
しず・さず → せず

To relate the 7 simplified bases to this system, consider the following chart.

Traditional vs. simplified japanese bases chart

The hardest part about this is naturally putting bases and endings together correctly on the spot. But regardless of what methodology you use, you’re still learning Japanese.

One key advantage to learning the traditional base system is that it is not limited to verbs. It applies to adjectives and auxiliaries. To learn more, check out:

This post was guest-authored by Seth Coonrod, a 19-year-old sophomore (at the time this article was written) at the University of Texas at Austin. He has been making ever since he was in 10th grade.

Over these years, his site has become immensely filled with lessons and data on 日本語. Though his work may still be relatively unknown online, you definitely need to check it out.

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