しぶとい (shibutoi) conjugation
tenacious, stubborn
しぶとい (しぶとい, shibutoi) is an i-adjective. I-adjectives carry their own tense: drop the final い and the endings attach straight to the stem. No だ, no です needed to make a complete sentence.
Conjugation table
| Form | Plain (casual) | Polite (~です) | When you use it |
|---|---|---|---|
| Dictionary / plain | しぶとい shibutoi | しぶといです shibutoidesu | The form you look up. Also the casual “is ~”. |
| Negative | しぶとくない shibutokunai | しぶとくないです shibutokunaidesu | “is not ~”. |
| Past | しぶとかった shibutokatta | しぶとかったです shibutokattadesu | “was ~”. |
| Past negative | しぶとくなかった shibutokunakatta | しぶとくなかったです shibutokunakattadesu | “was not ~”. |
| Te-form | しぶとくて shibutokute | — | Links to the next clause: “~ and …”. |
| Adverb | しぶとく shibutoku | — | Turns it into “~ly”, describing a verb. |
| Before a noun | しぶとい〜 shibutoi〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | しぶとければ shibutokereba | — | “if it is ~”. |
| Conditional (~たら) | しぶとかったら shibutokattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | しぶとくなる shibutokunaru | しぶとくなります shibutokunarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | しぶとすぎる shibutosugiru | しぶとすぎます shibutosugimasu | “too ~”. |
| Looks ~ (~そう) | しぶとそう shibutosou | しぶとそうです shibutosoudesu | “looks / seems ~” from appearance. |
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Why it conjugates this way
I-adjectives carry their own tense: drop the final い and the endings attach straight to the stem. No だ, no です needed to make a complete sentence.
See the full rules in the adjective conjugation guide.