noun
tree house
A small structure built in a tree, often for children's play or as a novelty accommodation.
子供たちは庭の大きな木にツリーハウスを作った。
The children built a tree house in the big tree in the garden.
あのキャンプ場にはツリーハウスに泊まれるプランがある。
That campsite has a plan where you can stay in a tree house.