What is the role of the な in bold in this sentence? Is it a nominalized だ?


1 Answer 1


Let's start with this part of the sentence:


We'd like to add のだ, which includes the nominalizer の. When we do this, だ changes to な, as you suggest:

+のだ = 〜のだ

Here's what our sentence looks like so far:


Since this has a question word, it's a question clause even without か. But we can add か anyway, and in this case it's required because of the following verb:


If this were a complete sentence, we'd want to delete だ before か:

彼女がどういう女なの     ← , not だか

But since the question clause is used as a complement for the following verb, deleting だ is optional:

考えれば考える程 [ 彼女がどういう女なのだか ] 分からなくなってきます。
考えれば考える程 [ 彼女がどういう女なのか ] 分からなくなってきます。

The last one is your sentence, so hopefully you can see how it's put together now.

  • Is deleting the だ actually optional here? This particular example sounds very strange to me with it.
    – rintaun
    Nov 23, 2013 at 20:26
  • @rintaun I think native speakers say things like 〜だか分からない fairly often. What do you think is different about this example?
    – user1478
    Nov 23, 2013 at 20:34
  • 1
    I've heard ~だか in embedded clauses many times, of course, but if I had to take a stab at what's making this sound unnatural to me, I would say it's the preceding なの. Remove either なの or だ and it sounds just fine to me. I'm certainly not a native speaker though, so that could just be a weird feature of my own interlanguage.
    – rintaun
    Nov 24, 2013 at 0:26
  • @rintaun Darius Jahandarie said the same thing in chat, but it's easy to find lots of examples of people saying 〜なのだか. Do you think the examples I listed in chat sound unnatural?
    – user1478
    Nov 24, 2013 at 0:28
  • 2
    ~~なのだか分からない is not only natural-sounding but also grammatical.
    – user4032
    Nov 24, 2013 at 1:02

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