Does anybody with in-depth knowledge of Old Japanese know why vowel-based verbal stems could only end in -e or -i (leading to the える/いる or type 2 class of verbs in Modern Japanese)? Why are there no cases of vowel based verbal stems ending in e.g. -a, -o or -u?

It is a very peculiar feature when compared to other languages that have conjugations based on the last letter/vowel of the verbal stem (such as Latin, Greek and Sanskrit)… Unfortunately my Japanese is rather rudimentary and my Old Japanese practically non-existent…

  • What do you mean by "vowel-based verbal stems"? And type 2 class of verbs? Jun 27, 2018 at 7:46
  • 1
    @BretonLoïc The former means exactly what it says: verbs (or "verbals") whose stems end in vowels. In Modern Japanese, an example would be taberu, whose stem is tabe-. Compare consonant-stem verbs like yomu, whose stem is yom-. The "type 2" terminology is just another way to refer to the class of vowel-stem verbs.
    – user1478
    Jun 27, 2018 at 7:58
  • Okay then, that's not really relevant to the question but all "vowel-ending verbal stems" didn't end up being "eru/iru" verbs in modern japanese: kobun.weblio.jp/content/%E3%82%91%E3%81%B5 ゑ・ふ which became よう (酔う) Jun 27, 2018 at 8:23
  • Like I said in the question, my Japanese is rather rudimentary and my Old Japanese practically inexistent, so I cannot really deliver an opinion on this… but… the wiktionary gives the etymology of 酔う as /wepu/ → /weɸu/ → /e.u/ → /yo.u/ This means this verb was originally a consonant-stem verb, as it ended in p, or later ɸ, although it might have functioned as a vowel-stem verb in an intermediary period...
    – Pregunto
    Jul 9, 2018 at 10:20

1 Answer 1


The capitalized Old Japanese (上代日本語) certainly has two vowel-stem types of verbs that yield today's -eru/-iru verbs respectively. However, it's not accurate to say they end in -e/-i because the language in the Old Japanese stage had 8 distinct "vowels", or to recent understanding, more like "rhymes":

a, i1, i2, u, e1, e2, o1, o2

which merged into the current 5-vowel system by the 9th century (then it becomes called Early Middle Japanese).

The two stem-final vowels you mentioned are actually -e2 and -i2, both of which were formed by contraction of adjacent vowels which are thought to have existed in earlier, pre-document ages. Since I don't have access to books such as Frellesvig (2010) now, just let me quote Wikipedia for an overview:

  • i2 < *ui: kami2/kamu- 'god, spirit', mi2/mu- 'eye', nagi2/nagu- 'a calm'.
  • i2 < *əi: ki2/ko2- 'tree', yomi2/yomo2- 'Hades'.
  • e2 < *ai: me2/ma- 'eye', ame2/ama- 'heaven', ame2/ama- 'rain', kage2/kaga- 'shade'.

Thus you can presume that some vowel-stem verbs were actually composed by underlying bases that end in other vowels, and suffixing *i.

aka "red, bright" / ake2- "brighten"
oko2-s- "raise up" / oki2- "arise"

  • This is an important point to make (+1), but I don't think you actually answer the question — why do vowel-stem verbs only end in -e or -i (or, after your explanation in -e₂ or -i₂)?
    – Earthliŋ
    Jun 27, 2018 at 10:19
  • @Earthliŋ Um... yes, you have a point :) Jun 27, 2018 at 17:23
  • What about the hypothesis that shimo-nidan verbs all come from eru? (Or am I getting things mixed up?)
    – Sjiveru
    Jun 27, 2018 at 20:00
  • 1
    @Sjiveru I think I've heard such thing on the discussion on the development of 可能動詞 (書く > 書ける), though. Jun 27, 2018 at 20:17
  • @broccoliforest There's that, too, but I seem to remember something about shimo-nidan verbs in general. (IIRC akeru is ichidan. I might be wrong, though.)
    – Sjiveru
    Jun 27, 2018 at 23:00

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .