I thought modern slangy verbs coined from onomatopoeia and loanwords were all godan verbs (for example, ググる, コピる, ピヨる, ボコる). This has been asked several times:

However, I recently noticed デレる might be an exception. In the general perspective, as this article suggests, デレる is a recent slang term coined from ツンデレ/デレデレ/デレ in the last few decades. However, it conjugates as an ichidan verb (デレない, デレました, デレた, デレろ rather than デレらない, デレりました, デレった, デレれ)!

Why is this? So far I have two hypotheses in mind...

  1. Is this because でれる is actually older than デレデレ, like 照れる is older than テレテレ?
    I found there was an example of でれる even in the meiji era. However, according to 青空文庫全文検索, デレデレ was a common word 100 years ago, and でれる was virtually nonexistent in those days. Still, I have no means to check how these words were used pre-Meiji. (Is there a public corpus for classical Japanese?)
  2. Is this because the stem of デレる ends with レ?
    Most (all?) verbs that end with れる are ichidan verbs (e.g., 入れる, 荒れる, 枯れる, 割れる), and デレれ does sound somehow weird to me. So it's not surprising if there is a rule that verbs ending with れる must be ichidan even if they are from loanwords/onomatopoeia. But I cannot think of any similar example (or counterexample) of this.

As an amateur language fan, I could affirm or negate neither of these two hypotheses. I believe I am not the first person who noticed this, so there may be a research about this. Any suggestion will be appreciated.

  • Regardless of historical usage I’m 99% sure hypothesis 2 would result in it being ichidan even if it was coined today, it just sounds better. (Totally just my opinion, but...) Nov 27, 2019 at 7:52
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    FYI: 手元の電子辞書に入っている精選版日本国語大辞典には「でれる」の用例として歌舞伎・善悪両面児手柏(妲己のお百)1867 二幕 「…お花ばうとでれ合って」が引かれています.「でれでれ」の用例は 1889年の落語となっていますが,項目としては後者が主として書かれていそうです(「でれる」の意味は「でれでれする」,「でれでれ」は別個に解説されている).
    – Yosh
    Nov 27, 2019 at 14:56
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    @Yosh ありがとうございます。そこまで古いと仮に「でれでれ」から「でれる」が産まれたのだとしても現代の造語法とは異なってて不思議はないですね…。こちらは「ナレった(ナレーションした)」という五段動詞っぽい例がちょっとだけ使われているのを見つけました(確かに何故か「ナレた」だと不自然な感じが…)。
    – naruto
    Nov 27, 2019 at 15:16
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    ばれる、ぐれる、ばえる(映える)は一段、だべるは五段、ぐでる(ぐでたま)は一段・五段両方観測されます。声優用語に「バレる」「ロレる」がありますが前者は一段、後者は五段… Nov 27, 2019 at 15:34
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    @broccoliforest おお…なんか「江戸期からあった古い俗語は一段」という予想が現実味を帯びてきた気がします…今だと「ぐれた」も「ぐれった」になるのかも…
    – naruto
    Nov 27, 2019 at 16:08

1 Answer 1


My current understanding is as follows (thank you Yosh and broccoli forest for the insightful comments).

デレる is an ichidan verb probably because it's actually an old verb coined in (or before) the 19th century, when the verb-coining rule was different from that of today. でれる did appear in several works in the 19th century. Although でれる was rare according to 青空文庫, it was common enough to be listed at least in three dictionaries. Several slangy verbs coined in this period were ichidan, and ぐれる (ichidan, "to turn delinquent", from ぐりはま) is a good example of this.

Hypothesis 1 is probably not correct because all the dictionary entries I checked so far explain でれる based on the meaning of でれでれ, which implies でれる derived from でれでれ, not the other way around.

Hypothesis 2 is not correct, either, because there are several more recent godan verbs whose stems end with れ:

  • ナレる: godan, "to narrate", from ナレーション (narration)
  • ロレる: godan, "(for a pronunciation) to be unclear; to slur", from 呂律

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