Meaning of verbal suffix ～てくたっとしてしまう


I've come across several cases of verbs with the suffix ～てくたっとしてしまう, but am
unsure how to break this suffix down, or what it means exactly. It seems that
this is the て-form of the base verb, followed by something that looks like
くたっ, perhaps followed by the particle と and the verb する in the て-form,
followed by the auxiliary verb しまう, but I'm having no luck finding a
grammatical description of the middle part here (くたっとする?).

A quick Google search finds many examples of sentences using this kind of
structure, such as:

  * きんぴらごぼうなども、そのまま鍋に入れておくと、余熱で火が通ってくたっとしてしまうので同じような処理をする。
  * レザーのクラッチバックというと重くてくたっとしてしまうイメージでしたが、これは全く違う印象でした。
  * 冬はさむくてくたっとしてしまうので、暖かいお部屋に入れてあげるか、いっそ球根（というかイモですね）で越冬させるか。

Would anyone be able to clarify the grammatical function at work here?




くたっ is a [mimetic](https://japanese.stackexchange.com/q/30335/5010) word
meaning something like "floppy", "tired", "withered", etc. It's a variation of
[くたくた / ぐだぐだ](http://jisho.org/word/%E3%81%8F%E3%81%9F%E3%81%8F%E3%81%9F).
くたっとする means "to become withered", etc.

When you have seen an unfamiliar mimetic/onomatopoeic word in the form of ～っと,
it's a good idea to repeat the mimetic/onomatopoeic part and look it up in a
dictionary. (e.g., look up にょきにょき instead of にょきっと) See: [How are the
giongo/gitaigo double form and tto form related (きらきら vs.
きらっと)](https://japanese.stackexchange.com/q/1479/5010)

You have parsed the remaining part correctly. To clarify, ～てくたっとしてしまう is not a
set "suffix" at all. It's just four words: ～て + くたっと + して + しまう, meaning
something like "and (it) ends up becoming floppy".




くたっ is a [mimetic](https://japanese.stackexchange.com/q/30335/5010) word
meaning something like "floppy", "tired", "withered", etc. It's a variation of
[くたくた / ぐだぐだ](http://jisho.org/word/%E3%81%8F%E3%81%9F%E3%81%8F%E3%81%9F).
くたっとする means "to become withered", etc.

When you have seen an unfamiliar mimetic/onomatopoeic word in the form of ～っと,
it's a good idea to repeat the mimetic/onomatopoeic part and look it up in a
dictionary. (e.g., look up にょきにょき instead of にょきっと) See: [How are the
giongo/gitaigo double form and tto form related (きらきら vs.
きらっと)](https://japanese.stackexchange.com/q/1479/5010)

You have parsed the remaining part correctly. To clarify, ～てくたっとしてしまう is not a
set "suffix" at all. It's just four words: ～て + くたっと + して + しまう, meaning
something like "and (it) ends up becoming floppy".

