Japanese Compound Verbs (複合動詞): ～出す, ～始める, ～続ける, ～合う & More

Introduction

Have you ever seen verbs like 降ふり出だす, 読よみ始はじめる, or 助たすけ合あう and wondered how they are built?

These are 複合動詞ふくごうどうし (compound verbs): two verbs joined into one.

Once you know the pattern, you can build dozens of new verbs from words you already know.

1. Meaning: What are compound verbs?

A compound verb takes the stem of one verb and attaches a second verb that adds meaning to it.

The first verb tells you what happens; the second tells you how it happens—suddenly, at the start, to the end, mutually, and so on.

This article covers seven of the most useful ones, in three groups.

① ～出だす → something starts suddenly

～出だす means the action begins abruptly and unexpectedly.

English equivalents include “suddenly start ~ing” and “burst out ~ing.”

It is especially common with inanimate subjects (rain, machines) and with involuntary human reactions (crying, laughing, getting angry).

Example: 降る＋出す→降り出す

急きゅうに雨あめが降ふり出だした。
It suddenly started raining.

② ～始はじめる／～終おわる／～続つづける → the stage of an action

These three mark where you are in an action.

• ～始める = begin to ~ (a normal, expected start)
• ～終わる = finish ~ing
• ～続ける = keep on ~ing

Note the contrast with ～出す: ～始める is neutral and often planned, while ～出す is sudden and unforeseen. Section 5 looks at this in detail.

③ ～忘わすれる／～合あう／～換かえる → other useful endings

• ～忘れる = forget to ~ (you meant to do it, but didn’t)
• ～合う = ~ each other / ~ together (a mutual action)
• ～換える = ~ and replace / swap

2. Formation

All seven work the same way:

Verb (ます-form) stem + 出だす／始はじめる／終おわる／続つづける／忘わすれる／合あう／換かえる

Take the ます form and drop ます:

• 踊おどる → 踊おどります → 踊おどり出す
• 読よむ → 読よみます → 読よみ始める
• 食たべる → 食たべます → 食たべ終わる
• 習ならう → 習ならいます → 習ならい続ける
• 言いう → 言いいます → 言いい忘れる
• する → します → 勉強べんきょうし始める

The compound then conjugates like a normal verb, following the second half:

• 降ふり出だす
  • 降り出した (past)
  • 降り出して (te-form)
  • 振り出します (masu-form)
• 食たべ終おわる
  • 食べ終わった (past)
  • 食べ終わって (te-form)
  • 食べ終わります (masu-form)

Particles stay the same

The compound keeps the particle the first verb would take.

• ごはんを食たべる (to eat a meal) → ごはんを食たべ終おわる (to finish eating)
• 友達ともだちと話はなす (to talk with friends) → 友達ともだちと話はなし合あう (to discuss things with friends)

Common combinations worth memorizing

～合う and ～換える in particular appear in a fixed set of everyday verbs:

～合う

• 助たすけ合あう (help each other)
• 話はなし合あう (discuss)
• 見みせ合あう (show each other)
• 言いい合あう (argue)
• 誘さそい合あう (invite each other)
• 送おくり合あう (send each other)

Practical tip: ～合う needs two or more parties, so the sentence normally includes と or a plural subject.

～換える

• 取とり換かえる (replace)
• 買かい換かえる (buy a replacement)
• 乗のり換かえる (transfer trains)
• 入いれ換かえる (swap in)

3. Useful Examples

① ～出す

Situation: John’s date yesterday did not go the way he expected.

John

デート中ちゅうに彼女かのじょが泣なき出だして、困こまったよ。
My girlfriend suddenly burst into tears in the middle of our date, leaving me at a loss for what to do.

Yumi

え、何なにがあったの？
Oh no, what happened?

突然とつぜんみんなが踊おどり出だしてびっくりした。
Everyone suddenly started dancing, and I was taken aback.

急きゅうに人形にんぎょうが動うごき出だして、みんなを驚おどろかせた。
The doll started moving and startled everyone.

② ～始める／～終わる／～続ける

Situation: Saori is ready to leave the restaurant, but Koki isn’t quite done.

Saori

そろそろ出でない？
Shall we get going soon?

Koki

もう少すこしで食たべ終おわるから、ちょっと待まって。
I’ll be finished eating in a minute, so hang on.

最近さいきん、新あたらしいマンガを読よみ始はじめました。
I recently started reading a new manga.

半年はんとしかけて、やっと論文ろんぶんを書かき終おわった。
It took half a year, but I finally finished writing my thesis.

3年前ねんまえから、日本語にほんごを習ならい続つづけています。
I’ve been learning Japanese continuously for three years.

このパソコンは5年ねんぐらい使つかい続つづけています。
I’ve kept using this computer for about five years.

③ ～忘れる／～合う／～換える

～忘れる

Situation: Koki remembers something on his way out of the office.

Koki

言いい忘わすれていましたが、来週らいしゅうの会議かいぎは3時じに変かわりました。
I forgot to mention this, but next week’s meeting has been moved to three o’clock.

Saori

そうなんですね。教おしえてくれて、ありがとうございます。
Oh, I see. Thanks for letting me know.

スープを作つくるとき、塩しおを入いれ忘わすれました。
I forgot to add salt when I was making soup.

～合う

仕事しごとが大変たいへんなときは同僚どうりょうと助たすけ合あいます。
When work gets tough, my colleagues and I help each other out.

教室きょうしつで学生がくせいたちがテストの結果けっかを見みせ合あっている。
The students are showing each other their test results in the classroom.

～換える

リモコンの電池でんちを取とり換かえます。
I’ll change the batteries in the remote.

冷蔵庫れいぞうこの調子ちょうしが悪わるかったので、新あたらしいのに買かい換かえました。
The fridge wasn’t working well, so I replaced it with a new one.

4. Related grammar (comparison)

～終おえる

～終える is the transitive partner of ～終わる.

It stresses that the subject deliberately brought the action to completion, and sounds a little more formal or written.

Example: I finished the homework and then played TV games.

宿題しゅくだいを終おえてからゲームをした。

In everyday conversation, ～終わる covers most situations.

～かける

～かける means the action is half-done or was started and left unfinished.

Compare it with ～始める, which simply says the action got underway.

• 何なにか言いいかけて、やめた。
  He started to say something, then stopped.
• テーブルに飲のみかけのコーヒーがある。
  There’s a half-drunk coffee on the table.

～切きる

～切る means to do something all the way, completely.

Where ～終わる just reports the end, ～切る adds a sense of achievement or exhaustion.

• マラソンを最後さいごまで走はしり切きった。
  I ran the marathon all the way to the finish.
• ケーキを一人ひとりで食たべ切きった。
  I ate the whole cake by myself.

～忘わすれる vs ～ことを忘わすれる

There is a subtle split between forgetting to do something and forgetting a fact.

• 薬くすりを飲のみ忘わすれた。= I forgot to take my medicine. (the action never happened)
• 薬くすりを飲のんだことを忘わすれた。= I forgot that I had taken my medicine. (it happened; the memory is gone)

5. Common Mistake: ～出だす vs. ～始はじめる

Both ～出す and ～始める can mean “start ~ing,” but they are used in different situations.

Compare these two sentences:

• 明日あしたから毎朝まいあさジョギングを始めようと思っています。
  I’m thinking of starting jogging every morning from tomorrow.
• 大おおきな犬いぬを見みて、子こどもが急きゅうに走はしり出した。
  The child suddenly started running when they saw a big dog.

～始める simply describes the beginning of an action or state.

It can be used for actions that you choose to start, as well as plans, requests, and invitations.

• 先生せんせいが来きたら、勉強べんきょうを始めましょう。
  Let’s start studying when the teacher arrives.
• 準備じゅんびができた人から、食たべ始めてください。
  Please start eating when you are ready.
• 来月らいげつから日本語にほんごを勉強し始めます。
  I’ll start studying Japanese next month.

～出す describes an action that starts suddenly or unexpectedly. It is often used when the start is not planned or when it happens in response to something.

• 突然とつぜん、赤あかちゃんが泣なき出した。
  The baby suddenly started crying.
• 雨あめが降ふり出したので、家いえに帰かえりました。
  It started raining, so I went home.
• 彼かれは急きゅうに歌うたい出した。
  He suddenly started singing.

Because ～出す often describes a sudden or unexpected start, it is not normally used for your own planned actions.

• ❌ 来月らいげつからピアノを習ならい出します。
• ✅ 来月らいげつからピアノを習ならい始めます。
  I’ll start learning piano next month.

6. Practice

Translate the following English into Japanese using a compound verb.

7. FAQ

Conclusion

In this article, you learned how 複合動詞ふくごうどうし (compound verbs) are built from the ます-stem plus a second verb, and met seven of the most useful endings.

With these compounds, you can now:

• mark the stage of an action with 始める、終わる、続ける,
• show that something began suddenly with ～出す,
• and express forgetting, mutual actions, and replacing in a single word with 忘れる、合う、換える.