The following words shall have the meaning expressed herein:
(a) "Helicopter" means a rotorcraft that, for its horizontal motion, depends principally on engine driven rotors.
(b) "Heliport" means an area of land, water, or structure used or intended to be used for the landing and takeoff of helicopters.
(c) "Helistop" means a location used for helicopter takeoffs and landings on a one time, a temporary, or an infrequent basis.
(d) "Imaginary Surfaces" means primary, approach-departure, horizontal, vertical, conical and transitional surfaces as established by the Federal Aviation Administration for obstruction determination purposes.
(1969 Code 103.02)