Hiatus reduction

Old japanese hiatus resolution

[vowel] + u

• a + u → ō
• (y)e + u → yō
  • a good example is kefu → kyō
    • kefu → keu → kyō
• i + u → yuu
• o + u → ō

^f

[vowel] + i

• a + i → ē
  • umai → umē
  • ja nai → ja nē
• e + i → ē
  • sensei → seNsē
• o + i → ē
  • sugoi → sugē
• u + i → ii
  • samui → samii

音便(おんびん)

i-onbin (イ音便)

Examples

• ki → i
  • kakite → kaite
  • akaki → akai
• ri → i
  • nasari → nasai
  • kudasari → kudasai
  • gozarimasu → gozaimasu

u-onbin (ウ音便)

• ku → u
  • ohayaku → ohayau (→ ohayou)
  • karaku → karau (→ karou)

soku-onbin (促音便)

• second morae of on-yomi when they have consonants (-ki, -ku, -chi, -tsu)
• second morae of on-yomi when it used to be -pu
  • gapusyou → gaQshou

hatsu-onbin (撥音便)

• mi, ni → N
  • yomite (te-form of yomu) → yoNde
  • sinite (te-form of shinu) → siNde
  • kamisashi → kaNzashi
  • nanide, nanito → naNde, naNto
• mu, nu → N
  • shiranufuri → shiraNpuri
  • masenu → maseN
• no → N
  • noda, node → Nda, Nde