費やす (tsuiyasu) conjugation
to spend, to devote, to waste
費やす (ついやす, tsuiyasu) is a godan verb. Godan verbs change their final kana up and down its column of the kana chart — the a-row for negatives, the i-row before ます, the e-row for potential and ば. Every form below is tappable — hear it, then say it back.
Conjugation table
| Form | Plain (casual) | Polite (~ます) | When you use it |
|---|---|---|---|
| Dictionary / plain | 費やす tsuiyasu | 費やします tsuiyashimasu | The form you look up. Also the casual present and future. |
| Plain negative | 費やさない tsuiyasanai | 費やしません tsuiyashimasen | “doesn’t / won’t”. From here it conjugates like an i-adjective. |
| Plain past | 費やした tsuiyashita | 費やしました tsuiyashimashita | The casual past — same ending as the te-form, with た/だ. |
| Plain past negative | 費やさなかった tsuiyasanakatta | 費やしませんでした tsuiyashimasendeshita | “didn’t”. The negative past, still i-adjective-shaped. |
| Te-form | 費やして tsuiyashite | — | The connector: requests, linking clauses, ~ている. |
| Progressive (~ている) | 費やしている tsuiyashiteiru | 費やしています tsuiyashiteimasu | “is ~ing”, or an ongoing resulting state. |
| Desire (~たい) | 費やしたい tsuiyashitai | 費やしたいです tsuiyashitaidesu | “want to ~”. Behaves as an i-adjective. |
| Volitional | 費やそう tsuiyasou | 費やしましょう tsuiyashimashou | “let’s ~” / “I think I’ll ~”. |
| Potential | 費やせる tsuiyaseru | 費やせます tsuiyasemasu | “can ~”. What you could do; the object often takes が. |
| Passive | 費やされる tsuiyasareru | 費やされます tsuiyasaremasu | “is ~ed”. Also the honorific and the suffering passive. |
| Causative | 費やさせる tsuiyasaseru | 費やさせます tsuiyasasemasu | Make or let someone do it. |
| Causative-passive | 費やさせられる tsuiyasaserareru | 費やさせられます tsuiyasaseraremasu | Be made to do it — the long one. |
| Imperative | 費やせ tsuiyase | 費やしてください tsuiyashitekudasai | Blunt order. Use ~てください in real life. |
| Prohibitive | 費やすな tsuiyasuna | — | “don’t!” — dictionary form + な. |
| Conditional (~ば) | 費やせば tsuiyaseba | — | “if ~”. General rules and hypotheticals. |
| Conditional (~たら) | 費やしたら tsuiyashitara | — | “if / when ~”. The everyday conditional. |
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Why it conjugates this way
Godan verbs change their final kana up and down its column of the kana chart — the a-row for negatives, the i-row before ます, the e-row for potential and ば.
See the full rules on the verb conjugation guide.