不規則 (fukisoku) conjugation
irregularity, unsteadiness
不規則 (ふきそく, fukisoku) 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 | 不規則だ fukisokuda | 不規則です fukisokudesu | The form you look up. Also the casual “is ~”. |
| Negative | 不規則じゃない fukisokujanai | 不規則じゃないです fukisokujanaidesu | “is not ~”. |
| Past | 不規則だった fukisokudatta | 不規則でした fukisokudeshita | “was ~”. |
| Past negative | 不規則じゃなかった fukisokujanakatta | 不規則じゃなかったです fukisokujanakattadesu | “was not ~”. |
| Te-form | 不規則で fukisokude | — | Links to the next clause: “~ and …”. |
| Adverb | 不規則に fukisokuni | — | Turns it into “~ly”, describing a verb. |
| Before a noun | 不規則な〜 fukisokuna〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | 不規則なら fukisokunara | — | “if it is ~”. |
| Conditional (~たら) | 不規則だったら fukisokudattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | 不規則になる fukisokuninaru | 不規則になります fukisokuninarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | 不規則すぎる fukisokusugiru | 不規則すぎます fukisokusugimasu | “too ~”. |
| Looks ~ (~そう) | 不規則そう fukisokusou | 不規則そうです fukisokusoudesu | “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.