活発 (kappatsu) conjugation
vigor, active
活発 (かっぱつ, kappatsu) is a na-adjective. Na-adjectives behave like nouns. The word itself never changes — you conjugate だ/です after it, and you need な to put it in front of a noun.
Conjugation table
| Form | Plain (casual) | Polite (~です) | When you use it |
|---|---|---|---|
| Dictionary / plain | 活発だ kappatsuda | 活発です kappatsudesu | The form you look up. Also the casual “is ~”. |
| Negative | 活発じゃない kappatsujanai | 活発じゃないです kappatsujanaidesu | “is not ~”. |
| Past | 活発だった kappatsudatta | 活発でした kappatsudeshita | “was ~”. |
| Past negative | 活発じゃなかった kappatsujanakatta | 活発じゃなかったです kappatsujanakattadesu | “was not ~”. |
| Te-form | 活発で kappatsude | — | Links to the next clause: “~ and …”. |
| Adverb | 活発に kappatsuni | — | Turns it into “~ly”, describing a verb. |
| Before a noun | 活発な〜 kappatsuna〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | 活発なら kappatsunara | — | “if it is ~”. |
| Conditional (~たら) | 活発だったら kappatsudattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | 活発になる kappatsuninaru | 活発になります kappatsuninarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | 活発すぎる kappatsusugiru | 活発すぎます kappatsusugimasu | “too ~”. |
| Looks ~ (~そう) | 活発そう kappatsusou | 活発そうです kappatsusoudesu | “looks / seems ~” from appearance. |
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Why it conjugates this way
Na-adjectives behave like nouns. The word itself never changes — you conjugate だ/です after it, and you need な to put it in front of a noun.
See the full rules in the adjective conjugation guide.