太い (futoi) conjugation
fat, thick
太い (ふとい, futoi) 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 | 太い futoi | 太いです futoidesu | The form you look up. Also the casual “is ~”. |
| Negative | 太くない futokunai | 太くないです futokunaidesu | “is not ~”. |
| Past | 太かった futokatta | 太かったです futokattadesu | “was ~”. |
| Past negative | 太くなかった futokunakatta | 太くなかったです futokunakattadesu | “was not ~”. |
| Te-form | 太くて futokute | — | Links to the next clause: “~ and …”. |
| Adverb | 太く futoku | — | Turns it into “~ly”, describing a verb. |
| Before a noun | 太い〜 futoi〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | 太ければ futokereba | — | “if it is ~”. |
| Conditional (~たら) | 太かったら futokattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | 太くなる futokunaru | 太くなります futokunarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | 太すぎる futosugiru | 太すぎます futosugimasu | “too ~”. |
| Looks ~ (~そう) | 太そう futosou | 太そうです futosoudesu | “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.