Dynamic lift—The lift given an airplane by the aerodynamic force produced from an adequately designed airfoil.
Glider—A fixed-wing aircraft having no power plant and constructed so as to glide and soar.
Gliding—The art, science, and activity of moving through the air in a glider.
Heavier-than-air aircraft—Any aircraft weighing more than the air it displaces.
Lift—That component of the total aerodynamic forces acting on an airfoil or on an entire aircraft or winged missile, perpendicular to the relative wind, and exerted, normally, in an upward direction opposing the pull of gravity.
Lighter-than-air aircraft—An aircraft that rises and is supported in air by virtue of a contained gas weighing less than the air displaced by the gas.
Nose dive—A steep dive by, or in, an aircraft.
Power plant—The complete engine or engines in an aircraft, together with propeller or propellers (if any), accessories, fuel and oil tanks and lines, etc.
Powered aircraft—An aircraft having one or more engines, as distinguished from a glider.
Tailspin—A spin, so named in reference to the characteristic spiral action of the tail when the airplane is in a spin.