1to stay (overnight) at a place (e.g., a hotel); to lodge.
今年の出張は東京のビジネスホテルに二泊三日で泊まる予定です。
For this business trip I plan to stay two nights at a Tokyo business hotel.
週末は友達の家に泊まってもいい？
Can I stay over at my friend's house on the weekend?
旅行中は地元の旅館に泊まるのが楽しみです。
I'm looking forward to staying at local ryokans during the trip.
2to be moored/berthed; to be docked (of a boat or ship).
台風のため、漁船は港に泊まったままだ。
Because of the typhoon, the fishing boats remained moored in the harbor.
あの客船は今夜ここに泊まる予定だ。
That cruise ship is scheduled to be berthed here tonight.