Editing Old Japanese (section)

==== Conjugation classes ====
{{see also|Japanese godan and ichidan verbs}}
Old Japanese verbs are classified into eight conjugation classes that were originally defined for the classical Japanese of the late Heian period. In each class, the inflected forms showed a different pattern of rows of a kana table.
These rows correspond to the five vowels of later Japanese, but the discovery of the A/B distinction in Old Japanese showed a more refined picture.{{sfn|Frellesvig|2010|p=115}}

Three of the classes are grouped as consonant bases:{{sfn|Frellesvig|2010|p=96}}
;{{wikt-lang|ja-Latn|四段活用|Yodan}} (quadrigrade)
:This class of regular consonant-base verbs includes approximately 75% of verbs.{{sfn|Frellesvig|2010|p=96}} The class is so named because the inflections in later forms of Japanese span four rows of a {{tlit|ja|kana}} table, corresponding to four vowels. However, the discovery of the A/B distinction revealed that this class actually involved five different vowels in Old Japanese, with distinct vowels ''e<sub>1</sub>'' and ''e<sub>2</sub>'' in the exclamatory and imperative forms respectively.{{sfn|Frellesvig|2010|p=115}} The bases are almost all of the form (C)VC-, with the final consonant being ''p'', ''t'', ''k'', ''b'', ''g'', ''m'', ''s'' or ''r''.{{sfn|Frellesvig|2010|p=97}}
;{{wikt-lang|ja-Latn|ナ行変格活用|Na-hen}} (''n''-irregular)
:The three ''n''-base verbs form a class of their own: {{tlit|ojp|sin-}} 'die', {{tlit|ojp|-in-}} 'depart' and the auxiliary {{tlit|ojp|-(i)n-}} expressing completion of an action. They are often described as a "hybrid" conjugation because the adnominal and exclamatory forms followed a similar pattern to vowel-base verbs.{{sfn|Frellesvig|2010|p=105}}
;{{wikt-lang|ja-Latn|ラ行変格活用|Ra-hen}} (''r''-irregular)
:The irregular ''r''-base verbs were {{tlit|ojp|ar-}} 'be, exist' and other verbs that incorporated it, as well as {{tlit|ojp|wor-}} 'be sitting', which became the existential verb {{tlit|ja|or-}} in later forms of Japanese.{{sfn|Frellesvig|2010|pp=101–103}}

{| class="wikitable"
|+ Conjugation of consonant-base verbs{{sfn|Frellesvig|2010|pp=54, 114}}
|-
! scope="col" | Verb class
! scope="col" | Irrealis !! scope="col" | Infinitive !! scope="col" | Conclusive !! scope="col" | Adnominal !! scope="col" | Exclamatory !! scope="col" | Imperative
! scope="col" | Gloss
|-
! scope="row" | quadrigrade
| {{tlit|ojp|kaka-}}
| {{tlit|ojp|kaki<sub>1</sub>}}
| {{tlit|ojp|kaku}}
| {{tlit|ojp|kaku}}
| {{tlit|ojp|kake<sub>2</sub>}}
| {{tlit|ojp|kake<sub>1</sub>}}
| 'write'
|-
! scope="row" | ''n''-irregular
| {{tlit|ojp|sina-}}
| {{tlit|ojp|sini}}
| {{tlit|ojp|sinu}}
| {{tlit|ojp|sinuru}}
| {{tlit|ojp|sinure}}
| {{tlit|ojp|sine}}
| 'die'
|-
! scope="row" | ''r''-irregular
| {{tlit|ojp|ara-}}
| {{tlit|ojp|ari}}
| {{tlit|ojp|ari}}
| {{tlit|ojp|aru}}
| {{tlit|ojp|are}}
| {{tlit|ojp|are}}
| 'be, exist'
|}

The distinctions between ''i<sub>1</sub>'' and ''i<sub>2</sub>'' and between ''e<sub>1</sub>'' and ''e<sub>2</sub>'' were eliminated after ''s'', ''z'', ''t'', ''d'', ''n'', ''y'', ''r'' and ''w''.

There were five vowel-base conjugation classes:
;{{wikt-lang|ja-Latn|下二段活用|Shimo nidan}} (lower bigrade or ''e''-bigrade)
:The largest regular vowel-base class ended in ''e<sub>2</sub>'' and included approximately 20% of verbs.{{sfn|Frellesvig|2010|p=97}}
;{{wikt-lang|ja-Latn|上二段活用|Kami nidan}} (upper bigrade or ''i''-bigrade)
:This class of bases ended in ''i<sub>2</sub>'' and included about 30 verbs.{{sfn|Frellesvig|2010|p=97}}
;{{wikt-lang|ja-Latn|上一段活用|Kami ichidan}} (upper monograde or ''i''-monograde)
:This class contains about 10 verbs of the form (C)''i<sub>1</sub>-''. Some monosyllabic ''i''-bigrade verbs had already shifted to this class by Old Japanese, and the rest followed in Early Middle Japanese.{{sfn|Frellesvig|2010|p=106}}
;{{wikt-lang|ja-Latn|カ行変格活用|Ka-hen}} (''k''-irregular)
:This class consists of the single verb {{tlit|ojp|ko<sub>2</sub>-}} 'come'.{{sfn|Frellesvig|2010|pp=107–108}}
;{{wikt-lang|ja-Latn|サ行変格活用|Sa-hen}} (''s''-irregular)
:This class consists of the single verb {{tlit|ojp|se-}} 'do'.{{sfn|Frellesvig|2010|pp=107–108}}
Early Middle Japanese also had a {{wikt-lang|ja-Latn|下一段活用|Shimo ichidan}} (lower monograde or ''e''-monograde) category, consisting of a single verb {{tlit|ojp|kwe-}} 'kick', which reflected the Old Japanese lower bigrade verb {{tlit|ojp|kuwe-}}.{{sfn|Frellesvig|2010|pp=227–228}}{{sfn|Yamaguchi|Suzuki|Sakanashi|Tsukimoto|1997|p=18}}{{sfn|Kondō|Tsukimoto|Sugiura|2005|p=41}}{{sfn|Omodaka|1967|pp=37–38}}

{| class="wikitable"
|+ Conjugation of vowel-base verbs{{sfn|Frellesvig|2010|pp=54, 114}}
|-
! scope="col" | Verb class
! scope="col" | Irrealis !! scope="col" | Infinitive !! scope="col" | Conclusive !! scope="col" | Adnominal !! scope="col" | Exclamatory !! scope="col" | Imperative
! scope="col" | Gloss
|-
! ''e''-bigrade
| {{tlit|ojp|ake<sub>2</sub>-}}
| {{tlit|ojp|ake<sub>2</sub>}}
| {{tlit|ojp|aku}}
| {{tlit|ojp|akuru}}
| {{tlit|ojp|akure}}
| {{tlit|ojp|ake<sub>2</sub>(yo<sub>2</sub>)}}
| 'open'
|-
! ''i''-bigrade
| {{tlit|ojp|oki<sub>2</sub>-}}
| {{tlit|ojp|oki<sub>2</sub>}}
| {{tlit|ojp|oku}}
| {{tlit|ojp|okuru}}
| {{tlit|ojp|okure}}
| {{tlit|ojp|oki<sub>2</sub>(yo<sub>2</sub>)}}
| 'arise'
|-
! monograde
| {{tlit|ojp|mi<sub>1</sub>-}}
| {{tlit|ojp|mi<sub>1</sub>}}
| {{tlit|ojp|mi<sub>1</sub>ru}}
| {{tlit|ojp|mi<sub>1</sub>ru}}
| {{tlit|ojp|mi<sub>1</sub>re}}
| {{tlit|ojp|mi<sub>1</sub>(yo<sub>2</sub>)}}
| 'see'
|-
! ''k''-irregular
| {{tlit|ojp|ko<sub>2</sub>-}}
| {{tlit|ojp|ki<sub>1</sub>}}
| {{tlit|ojp|ku}}
| {{tlit|ojp|kuru}}
| {{tlit|ojp|kure}}
| {{tlit|ojp|ko<sub>2</sub>}}
| 'come'
|-
! ''s''-irregular
| {{tlit|ojp|se-}}
| {{tlit|ojp|si}}
| {{tlit|ojp|su}}
| {{tlit|ojp|suru}}
| {{tlit|ojp|sure}}
| {{tlit|ojp|se(yo<sub>2</sub>)}}
| 'do'
|}

The bigrade verbs seem to belong to a later layer than other verbs.{{sfn|Frellesvig|2010|p=120}}
Many ''e''-bigrade verbs are [[transitive verb|transitive]] or [[intransitive verb|intransitive]] counterparts of consonant-base verbs.{{sfn|Frellesvig|2010|pp=118–119}}
In contrast, ''i''-bigrade verbs tend to be intransitive.{{sfn|Whitman|2008|p=164}}
Some bigrade bases also appear to reflect pre-Old-Japanese adjectives with vowel stems combined with an [[inchoative verb|inchoative]] *-i suffix:{{sfn|Unger|2000|p=665}}{{sfn|Frellesvig|2010|p=119}}{{sfn|Whitman|2008|p=165}}
* *-a-i > ''-e<sub>2</sub>'', e.g. {{tlit|ojp|ake<sub>2</sub>-}} 'redden, lighten' vs {{tlit|ojp|aka}} 'red'.
* *-u-i > ''-i<sub>2</sub>'', e.g. {{tlit|ojp|sabi<sub>2</sub>-}} 'get desolate, fade' vs {{tlit|ojp|sabu-}} 'lonely'.
* *-ə-i > ''-i<sub>2</sub>'', e.g. {{tlit|ojp|opi<sub>2</sub>-}} 'get big, grow' vs {{tlit|ojp|opo-}} 'big'.