臭い (kusai) conjugation
stinky, smelly, bad-smelling
臭い (くさい, kusai) is an i-adjective. I-adjectives carry their own tense: drop the final い and the endings attach straight to the stem. No だ, no です needed to make a complete sentence.
Conjugation table
| Form | Plain (casual) | Polite (~です) | When you use it |
|---|---|---|---|
| Dictionary / plain | 臭い kusai | 臭いです kusaidesu | The form you look up. Also the casual “is ~”. |
| Negative | 臭くない kusakunai | 臭くないです kusakunaidesu | “is not ~”. |
| Past | 臭かった kusakatta | 臭かったです kusakattadesu | “was ~”. |
| Past negative | 臭くなかった kusakunakatta | 臭くなかったです kusakunakattadesu | “was not ~”. |
| Te-form | 臭くて kusakute | — | Links to the next clause: “~ and …”. |
| Adverb | 臭く kusaku | — | Turns it into “~ly”, describing a verb. |
| Before a noun | 臭い〜 kusai〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | 臭ければ kusakereba | — | “if it is ~”. |
| Conditional (~たら) | 臭かったら kusakattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | 臭くなる kusakunaru | 臭くなります kusakunarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | 臭すぎる kusasugiru | 臭すぎます kusasugimasu | “too ~”. |
| Looks ~ (~そう) | 臭そう kusasou | 臭そうです kusasoudesu | “looks / seems ~” from appearance. |
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Why it conjugates this way
I-adjectives carry their own tense: drop the final い and the endings attach straight to the stem. No だ, no です needed to make a complete sentence.
See the full rules in the adjective conjugation guide.