偉大 (idai) conjugation
greatness
偉大 (いだい, idai) 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 | 偉大だ idaida | 偉大です idaidesu | The form you look up. Also the casual “is ~”. |
| Negative | 偉大じゃない idaijanai | 偉大じゃないです idaijanaidesu | “is not ~”. |
| Past | 偉大だった idaidatta | 偉大でした idaideshita | “was ~”. |
| Past negative | 偉大じゃなかった idaijanakatta | 偉大じゃなかったです idaijanakattadesu | “was not ~”. |
| Te-form | 偉大で idaide | — | Links to the next clause: “~ and …”. |
| Adverb | 偉大に idaini | — | Turns it into “~ly”, describing a verb. |
| Before a noun | 偉大な〜 idaina〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | 偉大なら idainara | — | “if it is ~”. |
| Conditional (~たら) | 偉大だったら idaidattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | 偉大になる idaininaru | 偉大になります idaininarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | 偉大すぎる idaisugiru | 偉大すぎます idaisugimasu | “too ~”. |
| Looks ~ (~そう) | 偉大そう idaisou | 偉大そうです idaisoudesu | “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.