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one
same (mind, path, etc.)
「一」 has other readings with different meanings.
意見が一致して安心した。
I was relieved that our opinions matched.
一時的な問題だから心配しないで。
It's a temporary problem, so don't worry.
一体何が起きたのか誰にも分からなかった。
Nobody knew what on earth had happened.