Editing Japanese grammar (section)

==={{nihongo|Euphonic changes|音便|onbin}}===
{{Main|Onbin}}

====Historical sound change====
<div style="float:right; margin-left:2em;">
{| class="wikitable"
|+ Spelling changes
! Archaic !! Modern
|-
| {{nihongo||あ＋う|a + u}}{{pb}}{{nihongo||あ＋ふ|a + fu}} || {{nihongo||おう|ō}}
|-
| {{nihongo||い＋う|i + u}}{{pb}}{{nihongo||い＋ふ|i + fu}} || {{nihongo||ゆう|yū}}<sup>1</sup>
|-
| {{nihongo||う＋ふ|u + fu}} || {{nihongo||うう|ū}}
|-
| {{nihongo||え＋う|e + u}}{{pb}}{{nihongo||え＋ふ|e + fu}} || {{nihongo||よう|yō}}
|-
| {{nihongo||お＋ふ|o + fu}} || {{nihongo||おう|ō}}
|-
| {{nihongo||お＋ほ|o + ho}}{{pb}}{{nihongo||お＋を|o + wo}} || {{nihongo||おお|ō}}
|-
| auxiliary verb {{nihongo||む|mu}} || {{nihongo||ん|n}}
|-
| medial or final {{nihongo||は|ha}} || {{nihongo||わ|wa}}
|-
| medial or final {{nihongo||ひ|hi}}, {{nihongo||へ|he}}, {{nihongo||ほ|ho}} || {{nihongo||い|i}}, {{nihongo||え|e}}, {{nihongo||お|o}}{{pb}}(via {{transliteration|ja|wi}}, {{transliteration|ja|we}}, {{transliteration|ja|wo}}, see below)
|-
| any {{nihongo||ゐ|wi}}, {{nihongo||ゑ|we}}, {{nihongo||を|wo}} || {{nihongo||い|i}}, {{nihongo||え|e}}, {{nihongo||お|o}}<sup>1</sup>
|}

# Usually not reflected in spelling
</div>

Modern pronunciation is a result of a long history of phonemic drift that can be traced back to written records of the 13th century, and possibly earlier. However, it was only in 1946 that the Japanese ministry of education modified existing [[kana]] usage to conform to the {{nihongo|standard dialect|共通語|kyōtsūgo}}. All earlier texts used the archaic orthography, now referred to as [[historical kana usage]]. The adjoining table is a nearly exhaustive list of these spelling changes.

Note that the palatalized morae {{lang|ja|ゆ}} and {{lang|ja|よ}} ({{transliteration|ja|yu}} and {{transliteration|ja|yo}}) combine with the initial consonant (if present) yielding a palatalized syllable. The most basic example of this is modern {{Nihongo3|today|今日（きょう）|kyō}}, which historically developed as {{Nihongo3||けふ|kefu}} → {{Nihongo3||きょう|kyō}}, via the {{Nihongo3||えふ|efu}} → {{Nihongo3||よう|yō}} rule.

A few sound changes are not reflected in the spelling. Firstly, {{transliteration|ja|ou}} merged with {{transliteration|ja|oo}}, both being pronounced as a long {{transliteration|ja|ō}}. Secondly, the particles {{lang|ja|は}} and {{lang|ja|を}} are still written using historical kana usage, though these are pronounced as {{transliteration|ja|wa}} and {{transliteration|ja|o}} respectively, rather than {{transliteration|ja|ha}} and {{transliteration|ja|wo}}.

Among Japanese speakers, it is not generally understood that the historical kana spellings were, at one point, reflective of pronunciation.{{Citation needed|date=November 2022}} For example, the modern {{transliteration|ja|on'yomi}} reading {{Nihongo3||よう|yō}} (for {{Nihongo|leaf|葉|yō}}) arose from the historical {{Nihongo3||えふ|efu}}. The latter was pronounced something like {{IPA|[ʲepu]}} by the Japanese at the time it was borrowed (compare [[Middle Chinese]] {{IPA|[jiɛp̚]}}). However, a modern reader of a classical text would still read this as {{IPAc-ja|yō}}, the modern pronunciation.

====Verb conjugations====
{{Main|Japanese verb conjugation}}

Conjugations of some verbs and adjectives differ from the prescribed formation rules because of euphonic changes. Nearly all of these euphonic changes are themselves regular. For verbs the exceptions are all in the ending of the continuative form of group when the following auxiliary starts with a {{transliteration|ja|t}}-sound (i.e. {{nihongo||-た|-ta}}, {{nihongo||-て|-te}}, {{nihongo||-たり|-tari}}, etc.).

{{clear}}

{| class="wikitable"
! Continuative ending !! Changes to !! Example
|-
| {{nihongo||い|i}}, {{nihongo||ち|chi}} or {{nihongo||り|ri}}
| {{lang|ja|っ}} ([[Gemination#Japanese|double consonant]], [[sokuon]], [[sokuonbin]])
| {{nihongo||＊買いて|*kaite}} → {{nihongo||買って|katte}}{{pb}}{{nihongo||＊打ちて|*uchite}} → {{nihongo||打って|utte}}{{pb}}{{nihongo||＊知りて|*shirite}} → {{nihongo||知って|shitte}}
|-
| {{nihongo||び|bi}}, {{nihongo||み|mi}} or {{nihongo||に|ni}}
| {{nihongo|syllabic {{transliteration|ja|n}}|ん}} ([[Japanese phonology#Moraic consonants|hatsuon]], [[hatsuonbin]]), with the following {{nihongo||タ|t}} sound [[consonant voicing|voiced]]
| {{nihongo||＊遊びて|*asobite}} → {{nihongo||遊んで|asonde}}{{pb}}{{nihongo||＊住みて|*sumite}} → {{nihongo||住んで|sunde}}{{pb}}{{nihongo||＊死にて|*shinite}} → {{nihongo||死んで|shinde}}
|-
| {{nihongo||き|ki}}
| {{nihongo||い|i}} ([[i-onbin]])
| {{nihongo||＊書きて|*kakite}} → {{nihongo||書いて|kaite}}
|-
| {{nihongo||ぎ|gi}}
| {{nihongo||い|i}}, with the following {{nihongo||タ|t}} sound voiced
| {{nihongo||＊泳ぎて|*oyogite}} → {{nihongo||泳いで|oyoide}}
|}

<nowiki>*</nowiki> denotes impossible/ungrammatical form.

There is one other irregular change: {{nihongo3|to go|行く|iku}}, for which there is an exceptional continuative form: {{nihongo||行き|iki}} + {{nihongo||て|te}} → {{nihongo||行って|itte}}, {{nihongo||行き|iki}} + {{nihongo||た|ta}} → {{nihongo||行った|itta}}, etc.

There are dialectical differences, which are also regular and generally occur in similar situations. For example, in [[Kansai dialect]] the {{transliteration|ja|-i}} + {{transliteration|ja|t-}} conjugations are instead changed to {{transliteration|ja|-ut-}} ([[u-onbin]]), as in {{Nihongo3||思うた|omōta}} instead of {{Nihongo3||思った|omotta}}, as perfective of {{Nihongo3|think|思う|omou}}. In this example, this can combine with the preceding vowel via historical sound changes, as in {{Nihongo3||しもうた|shimōta}} ({{transliteration|ja|au}} → {{transliteration|ja|ō}}) instead of standard {{Nihongo3||しまった|shimatta}}.

====Polite forms of adjectives====
The continuative form of proper adjectives, when followed by polite forms such as {{Nihongo3|be|ござる/御座る|gozaru}} or {{Nihongo3|know, think|存じる|zonjiru}}, undergoes a transformation; this may be followed by historical sound changes, yielding a one-step or two-step sound change. Note that these verbs are almost invariably conjugated to polite {{Nihongo3||〜ます|-masu}} form, as {{Nihongo3||ございます|gozaimasu}} and {{Nihongo3||存じます|zonjimasu}} (note the irregular conjugation of {{transliteration|ja|gozaru}}, discussed below), and that these verbs are preceded by the ''continuative'' form – {{Nihongo3||〜く|-ku}} – of adjectives, rather than the terminal form – {{Nihongo3||〜い|-i}} – which is used before the more everyday {{Nihongo3|be|です|desu}}.

The rule is {{Nihongo3||〜く|-ku}} → {{Nihongo3||〜う|-u}} (dropping the {{transliteration|ja|-k-}}), possibly also combining with the previous syllable according to the spelling reform chart, which may also undergo palatalization in the case of {{Nihongo3||ゆ、よ|yu, yo}}.

Historically there were two classes of proper [[Old Japanese#Adjectives|Old Japanese adjectives]], {{Nihongo3||〜く|-ku}} and {{Nihongo3||〜しく|-shiku}} ("{{transliteration|ja|-ku}} adjective" means "not preceded by {{transliteration|ja|shi}}"). This distinction collapsed during the evolution of [[Late Middle Japanese#Adjectives|Late Middle Japanese adjectives]], and both are now considered {{Nihongo3||〜い|-i}} adjectives. The sound change for {{transliteration|ja|-shii}} adjectives follows the same rule as for other {{transliteration|ja|-ii}} adjectives, notably that the preceding vowel also changes and the preceding mora undergoes palatalization, yielding {{Nihongo3||〜しく|-shiku}} → {{Nihongo3||〜しゅう|-shū}}, though historically this was considered a separate but parallel rule.

{| class=wikitable
! Continuative ending !! Changes to !! Example
|-
| {{nihongo||〜あく|-aku}}
| {{nihongo||〜おう|-ō}}
| {{nihongo||＊おはやくございます|*ohayaku gozaimasu}} →{{pb}}{{nihongo||おはようございます|ohayō gozaimasu}}
|-
| {{nihongo||〜いく|-iku}}
| {{nihongo||〜ゆう|-yū}}
| {{nihongo||＊大きくございます|*ōkiku gozaimasu}} →{{pb}}{{nihongo||大きゅうございます|ōkyū gozaimasu}}
|-
| {{nihongo||〜うく|-uku}}
| {{nihongo||〜うう|-ū}}
| {{nihongo||＊寒くございます|*samuku gozaimasu}} →{{pb}}{{nihongo||寒うございます|samū gozaimasu}}
|-
| {{nihongo||＊〜えく|*-eku}}
| {{nihongo||＊〜よう|*-yō}}
| (not present)
|-
| {{nihongo||〜おく|-oku}}
| {{nihongo||〜おう|-ō}}
| {{nihongo||＊面白くございます|*omoshiroku gozaimasu}} →{{pb}}{{nihongo||面白うございます|omoshirō gozaimasu}}
|-
| {{nihongo||〜しく|-shiku}}
| {{nihongo||〜しゅう|-shū}}
| {{nihongo||＊涼しくございます|*suzushiku gozaimasu}} →{{pb}}{{nihongo||涼しゅうございます|suzushū gozaimasu}}
|}

====Respectful verbs====
Respectful verbs such as {{nihongo3|'to get'|くださる|kudasaru}}, {{nihongo3|'to do'|なさる|nasaru}}, {{nihongo3|'to be'|ござる|gozaru}}, {{nihongo3|'to be/come/go'|いらっしゃる|irassharu}}, {{nihongo3|'to say'|おっしゃる|ossharu}}, etc. behave like group 1 verbs, except in the continuative and imperative forms.

{| class="wikitable"
! !! Change !! Example
|-
! continuative
| {{nihongo||〜り|-ri}} changed to {{nihongo||〜い|-i}} || {{nihongo||＊ござります|*gozarimasu}} → {{nihongo||ございます|gozaimasu}}{{pb}}{{nihongo||＊いらっしゃりませ|*irassharimase}} → {{nihongo||いらっしゃいませ|irasshaimase}}
|-
! imperative
| {{nihongo||〜れ|-re}} changed to {{nihongo||〜い|-i}} || {{nihongo||＊くだされ|*kudasare}} → {{nihongo||ください|kudasai}}{{pb}}{{nihongo||＊なされ|*nasare}} → {{nihongo||なさい|nasai}}
|}

====Colloquial contractions====
In speech, common combinations of conjugation and auxiliary verbs are contracted in a fairly regular manner.

{| class=wikitable
|+ Colloquial contractions
|-
! Full form || Colloquial !! Example
|-
| {{nihongo||〜てしまう|-te shimau}}
| {{nihongo||〜ちゃう/-ちまう|-chau/-chimau}}{{pb}}group 1
| {{fs interlinear|lang=ja
 | 負け'''て''' '''しまう''' → 負け'''ちゃう''' / 負け'''ちまう'''
 | make'''te''' '''shimau''' {} make'''chau''' / make'''chimau'''
 | 'lose'}}
|-
| {{nihongo||〜でしまう|-de shimau}}
| {{nihongo||〜じゃう/〜じまう|-jau/-jimau}}{{pb}}group 1
| {{fs interlinear|lang=ja
 | 死ん'''で''' '''しまう''' → 死ん'''じゃう''' / 死ん'''じまう'''
 | shin'''de''' '''shimau''' {} shin'''jau''' / shin'''jimau'''
 | 'die'}}
|-
| {{nihongo||〜ては|-te wa}}
| {{nihongo||〜ちゃ|-cha}}
| {{fs interlinear|lang=ja
 | 食べ'''て''' '''は''' いけない → 食べ'''ちゃ''' いけない
 | tabe'''te''' '''wa''' ikenai {} tabe'''cha''' ikenai
 | 'must not eat'}}
|-
| {{nihongo||〜では|-de wa}}
| {{nihongo||〜じゃ|-ja}}
| {{fs interlinear|lang=ja
 | 飲ん'''で''' '''は''' いけない → 飲ん'''じゃ''' いけない
 | non'''de''' '''wa''' ikenai {} non'''ja''' ikenai
 | 'must not drink'}}
|-
| {{nihongo||〜ている|-te iru}}
| {{nihongo||〜てる|-teru}}{{pb}}group 2b
| {{fs interlinear|lang=ja
 | 寝'''て''' '''いる''' → 寝'''てる'''
 | ne'''te''' '''iru''' {} ne'''teru'''
 | 'is sleeping'}}
|-
| {{nihongo||〜ておく|-te oku}}
| {{nihongo||〜とく|-toku}}{{pb}}group 1
| {{fs interlinear|lang=ja
 | し'''て''' '''おく''' → し'''とく'''
 | shi'''te''' '''oku''' {} shi'''toku'''
 | 'will do it so'}}
|-
| {{nihongo||〜て行く|-te iku}}
| {{nihongo||〜てく|-teku}}{{pb}}group 1
| {{fs interlinear|lang=ja
 | 出'''て''' '''行け''' → 出'''てけ'''
 | de'''te''' '''ike''' {} de'''teke'''
 | 'get out!'}}
|-
| {{nihongo||〜てあげる|-te ageru}}
| {{nihongo||〜たげる|-tageru}}{{pb}}group 2a
| {{fs interlinear|lang=ja
 | 買っ'''て''' '''あげる''' → 買っ'''たげる'''
 | kat'''te''' '''ageru''' {} kat'''tageru'''
 | 'buy something (for someone)'}}
|-
| {{nihongo||〜るの|-ru no}}
| {{nihongo||〜んの|-nno}}
| {{fs interlinear|lang=ja
 | 何 して い'''る''' '''の''' → 何 して'''んの'''
 | nani shite i'''ru''' '''no''' {} nani shite'''nno'''
 | 'what are you doing?'}}
|-
| {{nihongo||〜りなさい|-rinasai}}
| {{nihongo||〜んなさい|-nnasai}}
| {{fs interlinear|lang=ja
 | や'''りなさい''' → や'''んなさい'''
 | ya'''rinasai''' {} ya'''nnasai'''
 | 'do it!'}}
|-
| {{nihongo||〜るな|-runa}}
| {{nihongo||〜んな|-nna}}
| {{fs interlinear|lang=ja
 | や'''るな''' → や'''んな'''
 | ya'''runa''' {} ya'''nna'''
 | 'don't do it!'}}
|-
| {{nihongo||〜れは or 〜れば|-re wa or -reba}}
| {{nihongo||〜りゃ|-rya}}
| {{fs interlinear|lang=ja
 | どう す'''れば''' いい の だろう → どう す'''りゃ'''(あ） いいん だろう
 | dou su'''reba''' ii no darou {} dou su'''rya''' iin darou
 | 'what should I do?'}}
|}

There are occasional others, such as {{transliteration|ja|-aranai}} → {{transliteration|ja|-annai}} as in {{Nihongo3|don't understand|分からない|wakaranai}} → {{Nihongo3||分かんない|wakannai}} and {{Nihongo3|boring|つまらない|tsumaranai}} → {{Nihongo3||つまんない|tsumannai}} – these are considered quite casual and are more common among the younger generation.{{Citation needed|date=November 2021}}

Contractions differ by dialect, but behave similarly to the standard ones given above. For example, in the [[Kansai dialect]], {{Nihongo3||〜てしまう|-te shimau}} → {{Nihongo3||〜てまう|-temau}}.