http://www.thefreedictionary.com/plane
Word History: The plane in which we fly is properly named for a very important element of its structure
the wing that keeps it in the air. But the story behind this name is slightly complicated. To begin with, plane in the sense of "winged vehicle," first recorded in April 1908, is a shortened form ofaeroplane. In June of that year plane appeared in a quotation from the London Times that mentioned one of the Wright brothers. Aeroplane, first recorded in 1866, is made up of the prefix aero-, "air, aviation," and the word plane, referring to the structure designed to keep an air vehicle aloft. Originally the plane in such contexts was imagined as flat, hence the choice of the word plane; in practice this surface must curve slightly in order to work. The word aeroplane for the vehicle is first found in 1873. The first recorded appearance of the form airplane in our current sense, which uses air- instead ofaero-, is found in 1907. An American flies in an airplane while a Briton still travels in an aeroplane, but both can catch a plane.
air +plan
在空气 中 可以保持平衡的，一种工具。