The Japanese language has two main types of verbs which are referred to as and .
Categories are important when conjugating Japanese verbs, since conjugation patterns vary according to the verb's category. For example, and belong to different verb categories (pentagrade and monograde, respectively) and therefore follow different conjugation patterns. Most Japanese verbs are allocated into two categories:[1]
Statistically, there are far more pentagrade verbs[2] than monograde verbs.[3]
Sometimes categorization is expanded to include a third category of irregular verbs—which most notably include the verbs and . Classical Japanese had more verb groups, such as [4] and,[5] [6] which are archaic in Modern Japanese.
Within the terms and, the numbers and correspond with the number of rows that a verb stem (or inflectional suffix) can span in the gojūon kana table. This is best visualized by comparing various verb conjugations to an extracted column of the gojūon table:
| Pentagrade Form | Pentagrade Verb | Gojūon table 'ma' column | Monograde Form | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Negative | Polite | Dictionary | Potential | Volitional | |||||
| Negative | Japanese: 読'''ま'''ない | ||||||||
| Polite | Japanese: 読'''み'''ます | Japanese: '''み'''ない | Japanese: '''み'''ます | Japanese: '''み'''る | Japanese: '''み'''られる | Japanese: '''み'''よう | Monograde Verb | ||
| Dictionary (no conjugation) | Japanese: 読'''む''' | ||||||||
| Potential | Japanese: 読'''め'''る | Japanese: 止'''め'''ない | Japanese: 止'''め'''ます | Japanese: 止'''め'''る | Japanese: 止'''め'''られる | Japanese: 止'''め'''よう | Monograde Verb | ||
| Volitional | Japanese: 読'''も'''う | ||||||||
In the table above, the verb uses kana from all 5 rows of the gojūon table in its inflectional suffix—,,, and —amongst its conjugations. Thus, it is classified as a "class-5" (or more formally "pentagrade") verb. Meanwhile, the verbs and each use kana from only 1 row of the gojūon table in their verb-stem's suffix— and respectively. Thus, they are classified as a "class-1" (or more formally "monograde") verbs.
As monograde verbs only fall into the or rows, they can be further classified into the and subgroups respectively. This is due to being above in the vowel ordering.In full terminology, the gojūon column name of the verb stem's suffix becomes a prefix of these subgroups. For example, the monograde verb has its verb stem in the upper row of the and is formally classified as a verb; meanwhile, the monograde verb has its verb stem in the lower row of the 'ma' column and is formally classified as a verb.Pentagrade verbs are also formally classified into subgroups, but instead use the column name of the verb's inflectional suffix. For example, the pentagrade verb is in the 'ma' column, so it is formally classified as a verb.
Within Japanese language education, various terminologies are used in lieu of the Japanese nomenclature for "pentagrade" and "monograde" verbs.
| Pentagrade verbs | Monograde verbs | Example literature | |||
|---|---|---|---|---|---|
| Common terminology | Group 1 | Group 2 | Group 3 | A Dictionary of Basic Japanese Grammar | |
| Group I | Group II | Group III | |||
| Uncommon terminology | Irregular verbs | GENKI | |||
| Rare terminology | Consonant stem verbals | Vowel stem verbals | - |
In literature adopting the "Group I / II / III" terminology, the terms (I), (II) or (III) may be notated beside verbs.Similarly, (う) or (る) may be notated beside verbs in literature adopting the " / " terminology.
See also: Japanese verb conjugations.
The terms "consonant stem verbs" and "vowel stem verbs" come from a pattern that emerges from studying the actual structure of the words rather than the written representation. When considering the invariant part of the verb (the verb stem), the final phoneme determines the classification of the verb group. If the verb stem's final phoneme:
| Negative | | | | | |
|---|---|---|---|---|---|
| Polite form | | | | | |
| Plain form | | | | | |
| Potential form | | | | | |
| Volitional form | | | | | |
| Invariant rōmaji | |||||
| Final letter | m → consonant | r → consonant | i → vowel | e → vowel | |
| Classification | Consonant stem | Consonant stem | Vowel stem | Vowel stem | |
There are criticisms of the consonant and vowel nomenclature:
Classifying verbs is simple in theory:
verb-stem + {{nihongo krt||ない|nai}}verb-stem (ignoring the "{{nihongo2|ない}}"):| Negative verb | Last character of verb stem | Rhymes with | Group | |
|---|---|---|---|---|
| → | Pentagrade verb | |||
| → | Pentagrade verb | |||
| → | Monograde verb | |||
| → | Monograde verb |
This classification system works for all Japanese verbs, with three exceptions: is a pentagrade verb, and both and are instead classified as irregular verbs.[7]
In some Japanese dictionaries, the readings of conjugable words may have the stem and the inflectional suffix separated by a dot (・). For example, the adjective may be written as to separate the static prefix from the dynamic suffix.
This system also describes the verb group classification: in pentagrade verbs, the dot is placed before the last kana; in monograde verbs, the dot is placed before the last 2 kana (except for 2-kana monograde verbs, which have no dot).
However, regardless of the dot's position, the inflectional suffix is always the last kana of any monograde verb.
A caveat of accurately classifying verb groups is that you must have pre-existing knowledge of the verb's negative form. In practice, people tend to learn the verb's plain form first. As such, Japanese language educators usually teach strategies for naive verb classification. Whilst such strategies are not comprehensive, they generally remain useful in the context of regular daily conversations that language beginners will likely encounter. Here is one such strategy:
| Step | Verb (Plain Form) | If Yes | If Not | |
|---|---|---|---|---|
| 1 | Is the verb one of the most common "exceptions":,,,,,, | Pentagrade verb Group 1 | Go to Step 2 | |
| 2 | Does the verb suffix rhyme with or ? | Monograde verb Group 2 | Go to Step 3 | |
| 3 | Is the verb or ? | Irregular verb Group 3 | Pentagrade verb Group 1 |
Naive strategies, such as this one, tend to misidentify pentagrade verbs ending with —specifically, when pentagrade verbs rhyme with or . Therefore, when a monograde verb is concluded from a naive strategy, it is more efficient to confirm the verb's classification in a dictionary. However, there are other rules-of-thumb to more accurately discriminate such verbs.
If a dictionary is unavailable, it becomes difficult to discriminate pentagrade verbs from monograde verbs when they rhyme with or . The following heuristics aim to improve the accuracy of naive classification:
This includes verbs that rhyme with, and, which are pentagrade verbs.
248 of the 419 verbs [ca. 60%] listed in JMdict are pentagrade verbs.
2886 of the 3013 verbs [ca. 95%] listed in JMdict are monograde verbs.Kana and kanji based heuristics for and verbs:
There are many pentagrade verbs which may be mistaken for being monograde verbs in some cases
. On the surface, this may seem like a problem that only affects conjugation patterns, since pentagrade verbs and monograde verbs conjugate differently . However there are many verbs that, despite having the same spelling, have different meanings and belong to different verb groups. For example:
When reading verbs such as these, the correct word meaning can be ascertained through the different kanji or accentuation. However, ambiguity is usually removed if the verbs have been conjugated somehow, because different word groups conjugate with slightly varying pronunciations. For example:
| Verb conjugation | ||||||
|---|---|---|---|---|---|---|
| Pentagrade verb | Monograde verb | Pentagrade verb | Monograde verb | |||
| Negative | | | | | ||
| Polite form | | | | | ||
| Potential form | | | | | ||
| Volitional form | | | | | ||
Since there are so many pentagrade verbs that resemble monograde verbs, it is impractical to create or memorize an exhaustive list of words.