硬い (katai) conjugation
hard, firm, solid
硬い (かたい, katai) 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 | 硬い katai | 硬いです kataidesu | The form you look up. Also the casual “is ~”. |
| Negative | 硬くない katakunai | 硬くないです katakunaidesu | “is not ~”. |
| Past | 硬かった katakatta | 硬かったです katakattadesu | “was ~”. |
| Past negative | 硬くなかった katakunakatta | 硬くなかったです katakunakattadesu | “was not ~”. |
| Te-form | 硬くて katakute | — | Links to the next clause: “~ and …”. |
| Adverb | 硬く kataku | — | Turns it into “~ly”, describing a verb. |
| Before a noun | 硬い〜 katai〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | 硬ければ katakereba | — | “if it is ~”. |
| Conditional (~たら) | 硬かったら katakattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | 硬くなる katakunaru | 硬くなります katakunarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | 硬すぎる katasugiru | 硬すぎます katasugimasu | “too ~”. |
| Looks ~ (~そう) | 硬そう katasou | 硬そうです katasoudesu | “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.