Md. Code, Transportation § 11–169

(a) “Trailer” means, except as provided in subsection (b) of this section, a vehicle that:

(1) Has no motive power;

(2) Is designed to carry people or property and to be towed by a motor vehicle; and

(3) Is constructed so that no part of its weight rests on the towing vehicle.

(b) “Trailer” does not include a pole trailer.