In my understanding, the part of speech of a compound word is determined by
its ultimate morpheme. (複合語の品詞は、後にくる語（形態素）の品詞によって定まります)

> 蒸す(V)＋暑い(Adj) → 蒸し暑い(Adj)
>
> 持つ(V)＋物(N) → 持ち物(N)

and a verb in its -ず form can be roughly treated as an adverb.

> 食事をたいらげた ate up a meal
>
> 食事を残らずたいらげた ate up a meal completely (without any bit of remain)

Here comes the question. I find compound words ending with verb-ず have a
variety of 接続, none of them are used as an adverb, e.g.

> 知らずしらずのうちに (resembles noun＋の＋うち)
>
> 役立たずな人 (resembles 形容動詞＋な＋人)
>
> 恥知らず者 (resembles イ形容詞＋者)

How should I understand such a variety of 接続? and when to use which 接続?

p.s.

  1. I saw the subtitle "役立たず共め" in an anime, saw there is an example sentence "恥知らずなことをする" in my dictionary, and therefore I came up this question.
  2. I found compound words ending with verb-ず pretty versatile; it can be an adverb (in 日本人を恥知らず呼ばわりする外国人を批判する), a na-adjective (in 恥知らずな噓をつく), or a noun I guess? (in 馬鹿で恥知らずの人間になる) These three sentences are found on the Internet.
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2019-02-09T04:19:45.557
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question
grammar compounds
grammar - 接続 of compound words ending with verb-ず
If you already know [the masu-stem of some verbs can act as a noun or na-/no-
adjective](https://japanese.stackexchange.com/a/32311/5010), you can think
these ず-words are almost the same except that negation is included as part of
the word. That is to say, there are a few lexicalized ず-words that work as
nouns or na-/no-adjectives. Just like non-negative ones, many ず-words have
unpredictable meanings, and you have to learn them individually. 役立たず and 恥知らず
are typical examples, and they can safely work as nouns, na-adjectives and no-
adjectives.

Other examples:

  * 向こう見ず reckless
  * 親知らず wisdom tooth​
  * 医者要らず keeping doctor away
  * 水入らず en famille; private
  * 鳴かず飛ばず obscure; inactive; unsuccessful
  * 飲まず食わず without eating and drinking
  * 開かず (as in 開かずの間 locked/sealed room)
  * 寝ず (as in 寝ずの番 night watch)

This type of ず is integrated in a fossilized expression, and you cannot
arbitrarily add or remove it. For example, 恥知り and 向こう見 mean nothing. (Well,
飲み食い happens to mean something a bit different...) New words are very rarely
coined using this grammar, but
[おにぎらず](https://business.nikkeibp.co.jp/article/campanella/20150410/279842/)
is a fairly new buzzword made from おにぎり.
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2019-02-09T10:07:15.040
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answer