平凡 (heibon) conjugation
common, ordinary
平凡 (へいぼん, heibon) 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 | 平凡だ heibonda | 平凡です heibondesu | The form you look up. Also the casual “is ~”. |
| Negative | 平凡じゃない heibonjanai | 平凡じゃないです heibonjanaidesu | “is not ~”. |
| Past | 平凡だった heibondatta | 平凡でした heibondeshita | “was ~”. |
| Past negative | 平凡じゃなかった heibonjanakatta | 平凡じゃなかったです heibonjanakattadesu | “was not ~”. |
| Te-form | 平凡で heibonde | — | Links to the next clause: “~ and …”. |
| Adverb | 平凡に heibonni | — | Turns it into “~ly”, describing a verb. |
| Before a noun | 平凡な〜 heibonna〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | 平凡なら heibonnara | — | “if it is ~”. |
| Conditional (~たら) | 平凡だったら heibondattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | 平凡になる heibonninaru | 平凡になります heibonninarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | 平凡すぎる heibonsugiru | 平凡すぎます heibonsugimasu | “too ~”. |
| Looks ~ (~そう) | 平凡そう heibonsou | 平凡そうです heibonsoudesu | “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.