An aëroplane with a boatlike or other understructure that enables it to travel on, or to rise from the surface of, a body of water by its own motive power; -- now usually referred to as a seaplane.
Gnu Collaboartive International Dictionary of English: licensed under The Code Project Open License (CPOL)
Use "hydro-aeroplane" in a sentence
"Great American Four, the hydro-aeroplane champion, the M.P. champion pigeon-flyer, and the motor-bike hill-climbing champion."
"Assured from Dave's talk that he was not the Dawson boy, and that the hydro-aeroplane before him was not the Drifter, the man became very friendly."
""It is our new model of the composite hydro-aeroplane," explained the manager."