苦しい (kurushii) conjugation
tough; physically strenuous
苦しい (くるしい, kurushii) 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 | 苦しい kurushii | 苦しいです kurushiidesu | The form you look up. Also the casual “is ~”. |
| Negative | 苦しくない kurushikunai | 苦しくないです kurushikunaidesu | “is not ~”. |
| Past | 苦しかった kurushikatta | 苦しかったです kurushikattadesu | “was ~”. |
| Past negative | 苦しくなかった kurushikunakatta | 苦しくなかったです kurushikunakattadesu | “was not ~”. |
| Te-form | 苦しくて kurushikute | — | Links to the next clause: “~ and …”. |
| Adverb | 苦しく kurushiku | — | Turns it into “~ly”, describing a verb. |
| Before a noun | 苦しい〜 kurushii〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | 苦しければ kurushikereba | — | “if it is ~”. |
| Conditional (~たら) | 苦しかったら kurushikattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | 苦しくなる kurushikunaru | 苦しくなります kurushikunarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | 苦しすぎる kurushisugiru | 苦しすぎます kurushisugimasu | “too ~”. |
| Looks ~ (~そう) | 苦しそう kurushisou | 苦しそうです kurushisoudesu | “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.