This is the full reference paradigm for a godan verb ending in -ぐ, built on 泳ぐ（およぐ, "to swim"）. The -ぐ group is the voiced twin of the -く group: it takes the very same い-音便 softening in the te-form and past, but because ぐ is a voiced sound (it carries a 濁点／dakuten ゛), the voicing survives into the connector. So where 書く gives 書いて, 泳ぐ gives 泳いで — with a ゛ the -く verb never gets. Get that one dakuten right and the whole group is regular.
The stem walks the g-column
泳ぐ sits on the g-column. The g stays fixed; only the vowel changes:
- あ-row → 泳が (ga) — negative, causative, passive
- い-row → 泳ぎ (gi) — polite ます-stem
- う-row → 泳ぐ (gu) — dictionary
- え-row → 泳げ (ge) — potential, conditional, imperative
- お-row → 泳ご (go) — volitional
夏は毎週、海で泳ぐ。
natsu wa maishū, umi de oyogu
In summer I swim in the sea every week.
もっと速く泳げるようになりたい。
motto hayaku oyogeru yō ni naritai
I want to be able to swim faster.
The full paradigm — 泳ぐ
| Form | 泳ぐ (to swim) | Reading |
|---|---|---|
| Dictionary (plain non-past) | 泳ぐ | oyogu |
| Polite 〜ます | 泳ぎます | oyogimasu |
| Plain negative 〜ない | 泳がない | oyoganai |
| Polite negative 〜ません | 泳ぎません | oyogimasen |
| Plain past 〜だ | 泳いだ | oyoida |
| Plain past-negative 〜なかった | 泳がなかった | oyoganakatta |
| Te-form 〜で | 泳いで | oyoide |
| Potential (can) | 泳げる | oyogeru |
| Passive (受身) | 泳がれる | oyogareru |
| Causative (使役) | 泳がせる | oyogaseru |
| Causative-passive | 泳がせられる ／ 泳がされる | oyogaserareru / oyogasareru |
| Volitional 〜ごう | 泳ごう | oyogō |
| Conditional 〜ば | 泳げば | oyogeba |
| Conditional 〜たら | 泳いだら | oyoidara |
| Imperative (plain command) | 泳げ | oyoge |
| Prohibitive (negative command) | 泳ぐな | oyogu na |
The only cells that differ from a plain vowel-walk are the て／だ／だら trio (泳いで, 泳いだ, 泳いだら) — and even the conditional 〜たら inherits the voicing, becoming 〜だら. Everything else is a clean stroll across the g-column.
子どもの頃、よく近くの川で泳いだ。
kodomo no koro, yoku chikaku no kawa de oyoida
When I was a kid I often swam in the nearby river.
ここは流れが速いので、泳がないでください。
koko wa nagare ga hayai node, oyoganaide kudasai
The current here is strong, so please don't swim.
The te-form: 泳ぐ → 泳いで (voiced い-音便)
Just like -く, the ぐ softens to the vowel い before the connector. But ぐ is voiced, so the て itself is dragged into its voiced form で, and the past た into だ:
泳ぐ → 泳いで ／ 泳いだ ・ 急ぐ → 急いで ・ 脱ぐ → 脱いで ・ 稼ぐ → 稼いで ・ 注ぐ → 注いで
Compare the twins side by side — same い softening, opposite voicing:
| Ending | Dictionary | te-form | Past |
|---|---|---|---|
| く (unvoiced) | 書く | 書いて | 書いた |
| ぐ (voiced) | 泳ぐ | 泳いで | 泳いだ |
The voicing is not optional: every -ぐ verb produces で／だ, and ×泳いて／×泳いた are simply wrong. For the full group and its logic, see Godan ぐ → いで and the te/た sound-change chart.
急いで！バスがもう来るよ。
isoide! basu ga mō kuru yo
Hurry up — the bus is coming already!
靴を脱いで、そこに揃えて置いてね。
kutsu o nuide, soko ni soroete oite ne
Take off your shoes and line them up neatly there, okay?
彼はアルバイトで学費を稼いでいる。
kare wa arubaito de gakuhi o kaseide iru
He's earning his tuition through a part-time job.
Nasal-onset verbs sound like -んで — but aren't
One trap worth naming: because the で of 泳いで is voiced, learners sometimes confuse the ぐ group (いで) with the む・ぶ・ぬ group (んで). They both end in a voiced で, but the vowel before it is different: ぐ softens to い (泳いで), while む／ぶ／ぬ nasalize to ん (飲んで, 遊んで, 死んで). Match the softening to the ending: い for ぐ, ん for the nasals.
グラスにワインを注いでくれた。
gurasu ni wain o sosoide kureta
She poured me a glass of wine.
Potential 泳げる vs passive 泳がれる
Unlike the ichidan class, where potential and passive collapse into one form, godan verbs keep them cleanly apart, and 泳ぐ is a tidy illustration. The potential 泳げる ("can swim") is an everyday word; the passive 泳がれる is rare and, when it does appear, tends to be the indirect (suffering) passive — someone's swimming inconveniencing you — rather than a plain "is swum." Keep the え-row (potential) and あ-row (passive) stems distinct:
子どもがもう一人で泳げるようになった。
kodomo ga mō hitori de oyogeru yō ni natta
My kid can already swim on their own now. (potential)
狭いプールで隣を勢いよく泳がれると、ちょっと迷惑だ。
semai pūru de tonari o ikioi yoku oyogareru to, chotto meiwaku da
It's a bit annoying when someone swims hard right next to you in a small pool. (suffering passive)
Common mistakes
❌ 昨日、プールで泳いた。
kinō, pūru de oyoita
Incorrect — ぐ is voiced, so the past is 泳いだ with a dakuten, never ×泳いた.
✅ 昨日、プールで泳いだ。
kinō, pūru de oyoida
Yesterday I swam in the pool.
❌ 急いて用意してください。
isoite yōi shite kudasai
Incorrect — 急ぐ takes the voiced connector: 急いで, not ×急いて.
✅ 急いで用意してください。
isoide yōi shite kudasai
Please hurry and get ready.
❌ 玄関で靴を脱んで、揃えた。
Incorrect — that's the nasal ん of the む/ぶ/ぬ group; ぐ softens to the vowel い → 脱いで.
✅ 玄関で靴を脱いで、きれいに揃えた。
genkan de kutsu o nuide, kirei ni soroeta
I took off my shoes at the entrance and lined them up neatly.
❌ 川で泳ぎない。
kawa de oyoginai
Incorrect — the negative uses the あ-row 泳が, not the い-row stem.
✅ 川で泳がない。
kawa de oyoganai
I don't swim in the river.
The one error that defines this group is dropping the voicing — writing ×泳いて for 泳いで. If you ever hesitate, remember the dakuten is contagious: a voiced ending hands its voicing to the connector.
Key takeaways
- 泳ぐ is the model godan -ぐ verb. The g-column consonant is fixed; the vowel walks the rows.
- Te-form / past = 泳いで ／ 泳いだ — the same い-音便 as -く, but voiced (で／だ, with a dakuten).
- The voicing is obligatory: ×泳いて and ×泳いた are wrong for every -ぐ verb.
- Don't confuse ぐ → いで (vowel い) with the nasal group む/ぶ/ぬ → んで (nasal ん).
- Common -ぐ verbs: 泳ぐ, 急ぐ, 脱ぐ, 稼ぐ, 注ぐ, 騒ぐ, 防ぐ, 繋ぐ — all take いで／いだ.
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Start learning Japanese→Related Topics
- 書く: Full 五段 -く ParadigmN5 — The complete reference paradigm for a godan verb ending in -く, using 書く (to write): the い-音便 te-form 書いて and the one famous exception, 行く → 行って.
- te/ta Sound-Change (音便) Master ChartN4 — The definitive euphonic-change reference: every verb ending mapped to its te and た form, with the three 音便 types, the voicing rule, and the single 行く exception.
- 五段 Verbs: Class OverviewN5 — The canonical paradigm reference for the 五段 (godan / Type-1 / consonant-stem) class — the nine dictionary endings and the single mechanism behind every form: sliding the final kana across the あ・い・う・え・お rows.