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or; either ... or
maybe; perhaps; possibly
some ... and others ...; sometimes ... and at other times ...
電車、あるいはバスで行けますよ。
You can go by train or bus.
急げば或いは終電に間に合うかもしれない。
If we hurry, perhaps we might just make the last train.
今日、あるいは明日届くだろう。
It will probably arrive today or tomorrow.