truck tractor
Defined in 1 dictionary — U.S. Code
United States Code
49 U.S.C. § 31111 — in this section (3 versions over time)
Truck tractor.—The term "truck tractor" means—
(A) a non-property-carrying power unit that operates in combination with a semitrailer or trailer; or
(B) a power unit that carries as property motor vehicles when operating in combination with a semitrailer in transporting motor vehicles or any other commodity, including cargo or general freight on a backhaul.