高速 (kousoku) conjugation
high speed, high gear
高速 (こうそく, kousoku) 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 | 高速だ kousokuda | 高速です kousokudesu | The form you look up. Also the casual “is ~”. |
| Negative | 高速じゃない kousokujanai | 高速じゃないです kousokujanaidesu | “is not ~”. |
| Past | 高速だった kousokudatta | 高速でした kousokudeshita | “was ~”. |
| Past negative | 高速じゃなかった kousokujanakatta | 高速じゃなかったです kousokujanakattadesu | “was not ~”. |
| Te-form | 高速で kousokude | — | Links to the next clause: “~ and …”. |
| Adverb | 高速に kousokuni | — | Turns it into “~ly”, describing a verb. |
| Before a noun | 高速な〜 kousokuna〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | 高速なら kousokunara | — | “if it is ~”. |
| Conditional (~たら) | 高速だったら kousokudattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | 高速になる kousokuninaru | 高速になります kousokuninarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | 高速すぎる kousokusugiru | 高速すぎます kousokusugimasu | “too ~”. |
| Looks ~ (~そう) | 高速そう kousokusou | 高速そうです kousokusoudesu | “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.