Staying at the same place (e.g., hotel or ryokan) for two or more consecutive nights; commonly used in accommodation contexts.
出張でその週は同じホテルに連泊する予定だ。
I plan to stay at the same hotel for consecutive nights that week for my business trip.
夏休みは温泉旅館に連泊してゆっくり過ごしたい。
I want to spend my summer vacation staying several nights in a hot-spring inn to relax.
連泊すると割引が適用されるプランもある。
There are plans that offer discounts if you stay consecutive nights.