In romaji, the ways that verbs inflect is fairly straightforward to indicate. For example, if you wanted to describe the process under which 五段動詞{ごだんどうし} change from 辞書形{じしょけい} to 可能形{かのうけい}. One could say something like the following.

Replace the "-u" with "-eru."

Example: 飲む{のむ} → 飲める

Of course, this is assuming that we're aware of and abide by the linguistic rules of Japanese pronunciation, which means things like that if you have a "-tsu" ending and want to replace "-u" with "-eru", this really means to change "-tsu" to "-teru," not "-tseru."

If you wanted to make a note like this in Japanese, however, it's a little awkward.


It's awkward because this rule really applies to the u/e sounds and not the う・え kana specifically. For instance, if you wanted to apply this rule to the verb 飲む, it might be unclear what it means to replace 「~う」 with something when the kana う is not present.

How, in Japanese, does one denote in a short note form something like the "Replace the -u with -eru." sentence I indicated above?

  • Unable to find anything solid, but in searching I learned that the bit of the word that is conjugated is called the 活用語尾. tinyurl.com/sp2zyzz I would have to think that logic would apply with something like,活用語尾の「う」が「える」になる。But that's conjecture. Jan 19, 2020 at 20:11

1 Answer 1


You can use 段【だん】 (literally "column") to refer to the vowel of a kana. For example, エ段のカタカナ refers to エ, ケ, テ, and so on. (As an aside, 行【ぎょう】 refers to "row", i.e., consonant. ダ行のカタカナ refers to ダ, ヂ, ヅ, デ and ド.)

With this, the idea of:

Replace the "-u" with "-eru."

can be conveyed like so:

  • 最後の文字の母音をウ段からエ段に変えて「る」を付ける
  • 活用語尾をエ段に変えてルを足す

Of course, native Japanese speakers usually don't need a sentence like this, and someone who can read a sentence like this can also read romaji, too. Japanese Wikipedia doesn't explain this conjugation rule :)

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