天井

(1)the overhead upper surface of a covered space; "he hated painting the ceiling"

(2)部屋の内側の頭上の裏張り

(3)the inner top surface of a covered area or hollow space; "the roof of the cave was very high"; "I could see the roof of the bear's mouth"

(4)覆われた領域または空洞のスペースの内側の上の表面

(5)maximum altitude at which a plane can fly (under specified conditions)

(6)飛行機が飛ぶことができる最大高度（特定条件の下で）