Conjugable words

Stem forms

Prior to discussing the conjugable words, a brief note about stem forms. Conjugative suffixes and auxiliary verbs are attached to the stem forms of the affixee. In modern Japanese, there are the following six stem forms.

  • Terminal form (終止形 shuushikei) is used at the ends of clauses in predicate positions. This form is also variously known as plain form(基本形 kihonkei) or dictionary form (辞書形 jishokei).
  • Attributive form (連体形 rentaikei) in modern Japanese is practically identical to the terminal form (but see Adjectives, below), but differs in use: it is prefixed to nominals and is used to define or classify the noun. In this function, the root of this stem form is called a prenominal adjective (連体詞 rentaishi).
  • Continuative form (連用形 ren’yōkei) is used in a linking role. This is the most productive stem form, taking on a variety of endings and auxiliaries, and can even occur independently in a sense similar to the -te ending. This form is also used to negate adjectives.
  • Imperfective form (未然形 mizenkei) is used for plain negative (of verbs), causative and passive constructions. The most common use of this form is with the -nai auxiliary that turns verbs into their negative (predicate) form. (See Verbs below.)
  • Hypothetical form (仮定形 kateikei) is used for conditional and subjunctive forms, using the -ba or -domo ending.
  • Imperative form (命令形 meireikei) is used to turn verbs into commands. Adjectives do not have an imperative stem form.

The application of conjugative suffixes to stem forms follow certain euphonic principles (音便 onbin), which is discussed below.


Verbs in Japanese are rigidly constrained to the ends of clauses in what is known as the predicate position.

neko wa sakana o taberu
cat TOPIC fish OBJECT eats
(The) cat eats fish.

The subject and objects of the verb are indicated by means of particles (see the section on it below), and the grammatical functions of the verb—primarily tense and voice—are indicated by means of conjugation. When the subject and the dissertative topic coincide, the subject is often omitted; if the verb happens to be intransitive, then it might have no objects either, in which case the entire sentence consists of a single verb. For this reason, it is often claimed that verbs (or more accurately, predicates) are the most important parts of speech in Japanese. Verbs have two tenses indicated by conjugation— past and non-past. The semantic difference between present and future tenses is not indicated by means of conjugation. Usually, there is no ambiguity because few verbs can operate in both uses. Voice and aspect are also indicated by means of conjugation, and possibly agglutinating auxiliary verbs. For example, the continuative aspect is formed by means of the continuative conjugation known as the gerundive or -te form, and the auxiliary verb iru; to illustrate, 見る (miru, to see) → 見ている (mite-iru, is seeing).

Verbs can be semantically classified based on certain conjugations.

  • Stative verbs indicate existential properties, such as to be (いる iru), can do(出来る dekiru), need (要る iru), etc. These verbs generally don’t have a continuative conjugation with -iru because they are semantically continuative already.
  • Continual verbs conjugate with the auxiliary -iru to indicate the progressive aspect. Examples: to eat(食べる taberu), to drink (飲む nomu), to think(考える kangaeru). To illustrate the conjugation, 食べる (taberu, to eat) → 食べている (tabete-iru, is eating).
  • Punctual verbs conjugate with -iru to indicate a repeated action, or a continuing state after some action. Example: 知る (shiru, to know) → 知っている (shitte iru, am knowing); 打つ (utsu, to hit) → 打っている (utteiru, is hitting (repeatedly)).
  • Non-volitional verbs indicate uncontrollable action or emotion. These verbs generally have no volitional, imperative or potential conjugation. Examples: 好む (konomu, to like, emotive), 見える (mieru, to be visible, non-emotive).
  • Movement verbs indicate motion. Examples: 歩く (aruku, to walk), 帰る (kaeru, to return). In the continuative form (see below) they take the particle ni to indicate a purpose.
There are other possible classes and a large amount of overlap between the classes. Lexically, however, nearly every verb in Japanese is a member of exactly one of the following three regular conjugation groups.

  • Group 2a (上一段 kami ichidan, lit: upper first group) verbs with terminal stem form rhyming with -iru. Examples: 見る (miru, to see),着る (kiru, to wear).
  • Group 2b (下一段 shimo ichidan, lit: lower first group) verbs with terminal stem form rhyming with -eru. Examples: 食べる (taberu, to eat),くれる (kureru, to give).
  • Group 1 (五段 godan, lit: fifth group) verbs with terminal form rhyming with -u. This description has a slight ambiguity — certain verbs like 帰る (kaeru, to return) are group 1 instead of group 2. (See Miscellaneous section, below.) In modern Japanese the endings -yu and -fu are impossible, though they were common in classical Japanese; they are spelled with -u in modern Japanese.
Historical note: classical Japanese had upper and lower first and second groups and a fourth group(上/下一段 kami/shimo ichidan, 上/下二段 kami/shimonidan, and 四段 yodan), and nothing like the modern godan group. Since verbs have migrated across groups in the history of the language, conjugation of classical verbs is not predictable from a knowledge of modern Japanese alone.

Of the irregular classes, there are two:

sa-group (サ変 SA-hen, an abbreviation of サ行変格活用 SA-gyou henkaku katsuyō or SA-row irregular conjugation)
which has only one member, する (suru, to do).

ka-group (カ変 KA-hen, an abbreviation of カ行変格活用KA-gyou henkaku katsuyō)

which also has one member, 来る (kuru, to come).
Classical Japanese had one further irregular class, the na-group, which contained 死ぬ (shinu,to die) and a handful of other now rare verbs, but these verbs are regular group 1 verbs in modern Japanese.

The following table illustrates the stem forms of the above conjugation groups, with the root indicated with dots. For example, to find the hypothetical form of the group 1 verb 書く (kaku), look in the second row to find its root, ka, then in the hypothetical row to get the ending ke, giving the stem form kake. When there are multiple possibilities, they are listed in the order of increasing rarity.

使・ (tsuka.)書・ (ka.)見・ (mi.)食べ・ (tabe.)---
Attributive form

(連体形 rentaikei)

使う (.u)書く (.ku)見る (.ru)食べる (.ru)する (suru)来る (kuru)
Terminal form

(終止形 shuushikei)

same as attributive form-----
Continuative form

(連用形 ren'youkei)

使い (.i)書き (.ki)見 (.)食べ (.)し (shi)来 (ki)
Imperfective form

(未然形 mizenkei)

使わ (.wa)1書か (.ka)見 (.)食べ (.)し (shi)

せ (se)

さ (sa)

来 (ko)
Hypothetical form

(仮定形 kateikei)

使え (.e)書け (.ke)見れ (.re)食べれ (.re)すれ (sure)来れ (kure)
Imperative form

(命令形 meireikei)

使え (.e)書け (.ke)見ろ (.ro)

見よ (.yo)

食べろ (.ro)

食べよ (.yo)

しろ (shiro)

せよ (seyo)

せい (sei)

来い (koi)

  1. Note that this is an entirely different verb; する (suru) has no potential form.
The polite ending -masu conjugates as a group 1 verb. The passive and potential endings -reru and-rareru, and the causative endings -seru and -saseru all conjugate as group 2b verbs. Multiple verbal endings can therefore agglutinate. For example, a common formation is the causative-passive ending,-sase-rareru.

boku wa ane ni nattō o tabesaserareta.
I was made to eat natto by my (elder) sister.

As should be expected, the vast majority of lexically legal combinations of conjugative endings are not semantically meaningful.

Japanese Grammar Contents

  • Part 1: Textual classifications; nouns, pronouns, and other deictics
  • Part 2: Conjugable words: verbs
  • Part 3: Conjugable words: adjectives
  • Part 4: Conjugable words: the copula だ da
  • Part 5: Euphonic changes, colloquial contractions
  • Part 6: Adverbs, sound symbolism, conjunctions and interjections
  • Part 7: Particles
  • Part 8: Auxiliary verbs