I remember once I have seen 「なの」 was not placed at the end of a sentence (meaning it was not a question) ever since then I wondered what it meant but didn't have any clear examples. Today I saw this sentence in my textbook:


The textbook translates this sentence as "It is a boy, I know". The topic of the chapter is not about the 「なの」 part, so no explanation is given about it.

What does 「なの」 mean here?

Edit 1: Got the comma right in the translation. Sorry for misunderstanding!

  • I suggest you get a different textbook if it translates that as "It is a boy I know". Aug 25, 2014 at 22:43
  • Are you sure you're not missing a comma in "It is a boy, I know"?
    – dainichi
    Aug 25, 2014 at 23:09
  • @dainichi, my bad...
    – chlenix
    Aug 25, 2014 at 23:10
  • 1
    @chlenix Really? I find using "it" better than using "he" here. That is the nuance of the Japanese sentence in question anyway. Someone has a baby or a little kid and all you know is that it is a boy.
    – user4032
    Aug 25, 2014 at 23:59
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    @非回答者 Presumably it is the inversion, not the choice of pronoun which makes the supplied English translation unnatural for chlenix. (P.S., I chose "he" in my translation simply because "it" requires extra context to be permissible, and trying to set that up seemed rather tangential to what the question was asking about.) Aug 26, 2014 at 0:13

1 Answer 1


You can break なの down into the formal noun の and the adnominal copula な (i.e., a form of だ which shows up before nouns).

Your sentence: Basically, the sentence (彼が)男の子だ is embedded into は知ってる by turning it into a noun using の.


Alternatives: You could also write it as

"I know that he's a boy."

which is equivalent in meaning but slightly more formal/literary/whatever because it uses である in place of な to represent the copula. Another option is

"I'm aware of the fact that he's a boy."

which gets across the same point in a slightly more lengthy way.

If it was simply 男の子は知ってる that would either be read as "The boy knows" or "I know the boy", because there is no copula.

  • I certainly understood the "copula" you explained. Just a follow-up question if you don't mind me asking. How is の different than のは here then? Wouldn't [(彼が)男の子な]は知ってる get the same meaninga across as [(彼が)男の子な]のは知ってる ? I get the feeling that の is not possessive here, but something else. But I have no idea what that "something" is.
    – chlenix
    Aug 25, 2014 at 22:49
  • This は is actually the contrastive version of を. So, the thing marked by は is the object of 知ってる. There is a syntactic requirement that the object be a noun. The の (also こと if you are using である or という instead of な) plays the role of a dummy noun which doesn't actually mean anything and only serves to convert other things to nouns. You could gloss it as "fact" or "case" or whatever in English, but it's even lighter than those words so often the most natural translation is to not have a dummy noun in English at all. Aug 25, 2014 at 22:58
  • I know comments like "thanks" are discouraged but I just wanted to really thank you for your detailed explanations. On a side note, are there any online resources you would recommend besides Tae Kim's Grammar Guide, since you made me realize that the textbook I am using isn't particularly of a good quality (It's not Tae Kim's textbook, but another one). I hope asking for such isn't against the rules here.
    – chlenix
    Aug 25, 2014 at 23:04
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    No problem. I don't know any online resource which is completely satisfying, but in addition to Tae Kim's you can reference A logical Japanese grammar, An introduction to Japanese & 文法を楽しく along with corpora like 英辞郎, BCCWJ & Japanese Text Initiative, plus dictionaries like 大辞林. Aug 25, 2014 at 23:17

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