だ
Copula (Casual)
だ (da) is the casual version of です (desu). It means 'is', 'am', or 'are' and is used with nouns and na-adjectives.
How It Works
The copula だ is used to declare that 'A is B'.
1. Basic Conjugations
To become proficient in casual Japanese, you must learn the four basic forms of the copula:
- Present Affirmative: だ (is)
- Present Negative: じゃない (is not)
- Past Affirmative: だった (was)
- Past Negative: じゃなかった (was not)
2. Usage with Nouns and Na-Adjectives
It attaches directly to the end of a noun or a な-adjective.
- 学生（がくせい）だ。 (I am a student.)
- 静（しず）かだ。 (It is quiet.)
3. Register and Nuance
In spoken Japanese, ending a sentence with just だ can sound blunt. Speakers often omit it or add particles like よ or ね to soften it. While だ is common in fiction and personal essays, objective formal writing (like news or academic papers) typically uses である instead.
4. The 'Da to Na' Change
When だ appears in a subordinate clause before certain particles like ので or the nominalizer の, it must change to な.
- 学生なので... (Because I am a student...)
- 静かなのは... (The thing that is quiet is...)
5. Important Restriction
Unlike です, だ cannot follow an い-adjective. Saying おいしいだ is incorrect.
Examples (4)
- 今日は休みだ。
Today is a day off.
Word by Word: Today (topic) holiday is.
A simple statement of fact using a noun + だ.
- 彼はとても親切だ。
He is very kind.
Word by Word: He (topic) very kind is.
Using だ with the na-adjective 親切（しんせつ）.
- あ、あそこは学校だ。
Oh, that place over there is a school.
Word by Word: Ah, over there (topic) school is.
Used in an inner monologue or a casual observation when noticing something.
- 明日は雨だね。
It's rain tomorrow, right?
Word by Word: Tomorrow (topic) rain is (right?).
Adding the particle ね softens the bluntness of だ in conversation.
Common Mistakes
Using だ with i-adjectives.
このりんごはおいしいだ。このりんごはおいしい。Learners often think だ is exactly like です. While you can say おいしいです (polite), you cannot say おいしいだ. In casual speech, the い-adjective stands alone.
Using だ in casual questions with か.
学生だか？学生か？ / 学生？In casual speech, だ is dropped before the question particle か. Alternatively, just use a rising intonation on the noun itself.
How It Connects
Learn This First
To understand the casual copula 'だ', you need to know how basic Japanese sentences are structured and understand the difference between polite and casual speech styles.
Related Patterns
- ですCopula (Polite)
The polite version of the copula used in formal situations.
Level 1 - な-adjectives
These adjectives require だ to end a sentence in the plain form.
Level 1 - い-adjectives
Unlike nouns and na-adjectives, these cannot be followed by だ.
Level 1 - よAssertive Particle
Often added after だ to emphasize a statement or share new information.
Level 1 - ねConfirmation Particle
Often added after だ to seek agreement or confirm shared information.
Level 1 - Written style
The formal literary version of the plain copula used in academic writing.
Level 6
Learn Next
Patterns that build on this one.
- から（理由）BecauseLevel 1
- だからSo, ThereforeLevel 1
- かもしれないMight/maybeLevel 2
- そう（伝聞）I Heard ThatLevel 2
- ではなくてNot a but BLevel 2
- ならIf (Topic)Level 2
- の一つだOne ofLevel 2
- 〜にせよ/〜にしろEven If/whetherLevel 3
And 7 more in the full list.
Words in This Pattern
Practice だ in Bubblegum
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