深刻 (shinkoku) conjugation
serious
深刻 (しんこく, shinkoku) is a na-adjective. Na-adjectives behave like nouns. The word itself never changes — you conjugate だ/です after it, and you need な to put it in front of a noun.
Conjugation table
| Form | Plain (casual) | Polite (~です) | When you use it |
|---|---|---|---|
| Dictionary / plain | 深刻だ shinkokuda | 深刻です shinkokudesu | The form you look up. Also the casual “is ~”. |
| Negative | 深刻じゃない shinkokujanai | 深刻じゃないです shinkokujanaidesu | “is not ~”. |
| Past | 深刻だった shinkokudatta | 深刻でした shinkokudeshita | “was ~”. |
| Past negative | 深刻じゃなかった shinkokujanakatta | 深刻じゃなかったです shinkokujanakattadesu | “was not ~”. |
| Te-form | 深刻で shinkokude | — | Links to the next clause: “~ and …”. |
| Adverb | 深刻に shinkokuni | — | Turns it into “~ly”, describing a verb. |
| Before a noun | 深刻な〜 shinkokuna〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | 深刻なら shinkokunara | — | “if it is ~”. |
| Conditional (~たら) | 深刻だったら shinkokudattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | 深刻になる shinkokuninaru | 深刻になります shinkokuninarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | 深刻すぎる shinkokusugiru | 深刻すぎます shinkokusugimasu | “too ~”. |
| Looks ~ (~そう) | 深刻そう shinkokusou | 深刻そうです shinkokusoudesu | “looks / seems ~” from appearance. |
🔊 Tap any Japanese word to hear it spoken.
Why it conjugates this way
Na-adjectives behave like nouns. The word itself never changes — you conjugate だ/です after it, and you need な to put it in front of a noun.
See the full rules in the adjective conjugation guide.