忙しい (isogashii) conjugation
busy (people, days)
忙しい (いそがしい, isogashii) 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 | 忙しい isogashii | 忙しいです isogashiidesu | The form you look up. Also the casual “is ~”. |
| Negative | 忙しくない isogashikunai | 忙しくないです isogashikunaidesu | “is not ~”. |
| Past | 忙しかった isogashikatta | 忙しかったです isogashikattadesu | “was ~”. |
| Past negative | 忙しくなかった isogashikunakatta | 忙しくなかったです isogashikunakattadesu | “was not ~”. |
| Te-form | 忙しくて isogashikute | — | Links to the next clause: “~ and …”. |
| Adverb | 忙しく isogashiku | — | Turns it into “~ly”, describing a verb. |
| Before a noun | 忙しい〜 isogashii〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | 忙しければ isogashikereba | — | “if it is ~”. |
| Conditional (~たら) | 忙しかったら isogashikattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | 忙しくなる isogashikunaru | 忙しくなります isogashikunarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | 忙しすぎる isogashisugiru | 忙しすぎます isogashisugimasu | “too ~”. |
| Looks ~ (~そう) | 忙しそう isogashisou | 忙しそうです isogashisoudesu | “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.