Use 連用形 as a 形容動詞 (na-adjective)

Question

In the lyric of 余白 by 尾崎由香, there is the line

言わば引きこもりなくせに

In this line, the 連用形 of the verb 引きこもる seems to be used as a 形容動詞. While it is quite common to use the 連用形 of a verb as a noun, this is the first time I see 連用形 used as a 形容動詞 if I remember correctly. In this particular case, I did some search and found many examples with "引きこもりのくせ", which is using the 連用形 as a noun in the usual way, but I am not sure whether there are any cases where the 連用形 can only be used as a 形容動詞.

So under what conditions can the 連用形 be used as 形容動詞 and can I tell it from the verb itself?

Answer 1

It seems a difficult set of conditions to satisfy. If a word derived from a verb is used as an adjective, it most likely describes a person’s tendency to behave in a certain way. But such an adjective tends to be used also as a noun to refer to the kind of person it describes.

As examples, I can think of those that end with がり, such as 怖がり, 寒がり, and 面倒くさがり. These are used as both adjectives and nouns. Interestingly, 怖がりな人 produces more search results than 怖がりの人. whereas 寒がりな人 much fewer than 寒がりの人.

In comparison, 引きこもり is more clearly a noun. I find 引きこもりな人 a bit weird. However, it doesn’t surprise me that some people use this kind of noun as an adjective. The distinction often gets blurred.