妥当 (datou) conjugation
proper, appropriate
妥当 (だとう, datou) 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 | 妥当だ datouda | 妥当です datoudesu | The form you look up. Also the casual “is ~”. |
| Negative | 妥当じゃない datoujanai | 妥当じゃないです datoujanaidesu | “is not ~”. |
| Past | 妥当だった datoudatta | 妥当でした datoudeshita | “was ~”. |
| Past negative | 妥当じゃなかった datoujanakatta | 妥当じゃなかったです datoujanakattadesu | “was not ~”. |
| Te-form | 妥当で datoude | — | Links to the next clause: “~ and …”. |
| Adverb | 妥当に datouni | — | Turns it into “~ly”, describing a verb. |
| Before a noun | 妥当な〜 datouna〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | 妥当なら datounara | — | “if it is ~”. |
| Conditional (~たら) | 妥当だったら datoudattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | 妥当になる datouninaru | 妥当になります datouninarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | 妥当すぎる datousugiru | 妥当すぎます datousugimasu | “too ~”. |
| Looks ~ (~そう) | 妥当そう datousou | 妥当そうです datousoudesu | “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.