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to happen to meet; to come across; to run into; to bump into
散歩中に偶然昔の友人に出くわして驚いた。
I was surprised to come across an old friend while walking.
山で野生の熊に出くわしたら冷静に対処すべきだ。
If you encounter a wild bear in the mountains, you should stay calm.
思いがけない場所で元上司に出くわしてしまった。
I happened to run into my former boss in an unexpected place.