Editing Japanese grammar (section)

====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}}
|}