1To come off, come loose, or slip out of place—said of something attached (a button, screw, gear, etc.) becoming detached.
シャツのボタンが外れてしまった。
A button on my shirt came off.
棚が外れて本が床に落ちた。
The shelf came loose and the books fell to the floor.
自転車のチェーンが外れて走れなくなった。
The bicycle chain came off and I couldn't ride it anymore.
ドアの取っ手が外れて修理が必要だ。
The door handle came off and needs to be repaired.
2To miss the mark or be wrong—used when a prediction, guess, or expectation turns out different from reality (e.g., not winning a lottery, a forecast being wrong).
天気予報が外れて、急に雨が降ってきた。
The weather forecast was wrong, and it suddenly started raining.
今回の宝くじも外れてしまった。
I lost the lottery again this time.
彼の推理は外れていて、犯人は別の人だった。
His deduction was wrong—the culprit turned out to be someone else.
3To be removed or excluded from something, such as a list, group, or plan.
人数が多すぎて、彼の名前は候補から外れてしまった。
There were too many candidates, so his name was dropped from the list.
けがのため、彼は次の試合のメンバーから外れた。
Due to injury, he was left off the roster for the next match.
その案は予算の都合で計画から外れることになった。
Due to budget constraints, that proposal ended up being dropped from the plan.
4To be contrary to or deviate from something expected, such as common sense, rules, or standards.
彼のやり方は会社のルールから外れている。
His way of doing things goes against the company's rules.
その意見は議題から外れているので、後で話しましょう。
That opinion is off-topic, so let's discuss it later.
話が本題から外れてしまった。
The conversation strayed from the main topic.