I've been learning Japanese for a while, but I usually use 敬語, like です、ます, so I still can not understand how to use something that is not 敬語 correctly, especially the 終助詞. Like の and だ.

For example, 私は大丈夫 and 私は大丈夫だ. How to use them correctly?

And I now know の can mean a question at the end of a sentence, but sometimes it does not mean a question, and I don't know what it means when it's not a question. And what is the difference between の and のだ ?

For example, 猫が好きだ。猫が好きなの。猫が好きなのだ。What is the difference?

Also, I have been told that only woman can use の at the end of a sentence when it is not a question, but what about man? When man wants to express the exact same meaning as the one woman says with の at the end of it, what can he use?

For example, how can a man say "猫が好きなの"?

Thank you so much.

  • Actually, だ does not fall into the same category with の. の is a particle, while だ is an auxiliary......
    – user7644
    Commented Aug 6, 2015 at 13:26
  • Yeah, I'm aware of that. Thank you for pointing that out. But in this case, their use just seems so alike, and they have made me confused for a long time. I'm afraid of speaking without using 敬語 even now.
    – Yang
    Commented Aug 6, 2015 at 15:46

1 Answer 1


だ is called a copula, roughly translating to the English verb "to be" (is, are, am, etc.). It is not a particle but a suffix that attaches to the end of nouns and adjectival nouns (na-adjectives). It is used in informal conversation, as opposed to its polite counterpart です, which it seems you already know. Like です, its basic use is to equate two things as equal; in other words, to say one thing is another thing.

私は学生 - I am a student.
彼は大丈夫 - He is all right

As I stated somewhere in the first paragraph, you can only attach it to nouns and na-adjectives (which are nouns that behave like adjectives). You cannot attach it to i-adjectives; they stand on their own at the end in informal speech. This is where だ differs from です, which attaches to i-adjectives.

× 食べ物はおいしいだ
○ 食べ物はおいしい

Also unlike です, which only really appears at the end of the main clause, だ often appears at the end of quotations and subordinate clauses (but not relative clauses), even if the whole sentence is polite.

元気だと言った - He said he was fine.
冬だから客もあまりいません - Because it's winter, there aren't many customers.

The negative of だ is じゃない, which now, just like the negative form of verbs, conjugates like an i-adjective (so the negative past is じゃなかった, the -て form is じゃなくて, etc.).

私は学生じゃない - I am not a student.
友達じゃない - (He) isn't my friend.
全然好きじゃなかった - (I) didn't like it at all.

Grammatically speaking, だ and じゃない are always required. You can't end a sentence with a noun.

× 私は大丈夫
○ 私は大丈夫だ

However, since it's informal speech, this rule is frequently ignored.

When used as a sentence-ending particle, の can generally do one of two things to a sentence, neither of which have the same function as だ. Firstly, it can emphasize emotion. This usage is used mostly by women or children.

ブロッコリーが好きじゃないの - I don't like broccoli

Secondly, it can be used as an explanation, or in other words, to fill in an "information deficit". This の is basically the same thing as のだ/んだ, but with the だ dropped. See more information about the のだ/んだ construction and meaning here or here. の as a question marker applies to this as well- it is the short and informal form of のですか.

今は忙しいの - I am busy (as an explanation)
お腹が空いたの - I was hungry (as an explanation)
どこに行くの(ですか) - Where are you going?

It is a little more complicated than that, but the links above should be good at explaining what の/のだ is used for as opposed to normal statements and questions.

Note, though, that sentence-ending の must be preceded by な if the preceding word is a noun so that it can be distinguished from the other uses of の.

私のだ - it is mine
私なのだ - it is me (as an explanation).

  • Thank you so much for answering. I am just not so sure of how to use them. Can I ask you some other question? You said "You can't end a sentence with a noun", but I have heard both are been used with or without だ even in an informal speech, what's the difference in that situation? Because when Japanese are injured, they would only say 大丈夫 instead of 大丈夫だ. And for の, in the first function you said, it can not be replaced by のだ right? And if a man wants to express the same meaning without using の, how can he say? And in the second function, it is totally the same as のだ?
    – Yang
    Commented Aug 8, 2015 at 0:45
  • @Yang 1) I actually did say that the rule of ending in a noun is often ignored in informal speech, even though it's grammatically incorrect. 2) you are correct, the first function of の wouldn't have だ after it (otherwise it would be confused with the other one). 3) Unfortunately I'm not sure how to answer this one. I'm guessing a male could use it if he wanted, but it would sound feminine, or just wouldn't use it at all (since it's not super important to the meaning of the sentence.) I am sorry. 4) Correct again, same function as のだ.
    – Blavius
    Commented Aug 8, 2015 at 1:06
  • Thank you. It's just I thought I felt a little difference when だ is used and not used. Maybe that's just my 勘違い. Anyway, thank you so much for being so patient with me.
    – Yang
    Commented Aug 11, 2015 at 5:05

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