Hy"dro*plane (?), n. [Pref. hydro- (1.) + plane.]
1.
A plane, or any of a number of planes, projecting from the hull of a submarine boat, which by being elevated or depressed cause the boat, when going ahead, to sink or rise, after the manner of an aëroplane.
2.
A projecting plane or fin on a gliding boat to lift the moving boat on top of the water; also, a gliding boat.
© Webster 1913.
Hy"dro*plane, v. i.
Of a boat, to plane (see Plane).
© Webster 1913.