でかい (dekai) conjugation
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でかい (でかい, dekai) 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 | でかい dekai | でかいです dekaidesu | The form you look up. Also the casual “is ~”. |
| Negative | でかくない dekakunai | でかくないです dekakunaidesu | “is not ~”. |
| Past | でかかった dekakatta | でかかったです dekakattadesu | “was ~”. |
| Past negative | でかくなかった dekakunakatta | でかくなかったです dekakunakattadesu | “was not ~”. |
| Te-form | でかくて dekakute | — | Links to the next clause: “~ and …”. |
| Adverb | でかく dekaku | — | Turns it into “~ly”, describing a verb. |
| Before a noun | でかい〜 dekai〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | でかければ dekakereba | — | “if it is ~”. |
| Conditional (~たら) | でかかったら dekakattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | でかくなる dekakunaru | でかくなります dekakunarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | でかすぎる dekasugiru | でかすぎます dekasugimasu | “too ~”. |
| Looks ~ (~そう) | でかそう dekasou | でかそうです dekasoudesu | “looks / seems ~” from appearance. |
🔊 Tap any Japanese word to hear it spoken.
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.