In this chapter:
(1) "Load" means a load of loose material.
(2) "Loose material" means material that can be blown or spilled from a vehicle because of movement or exposure to air, wind currents, or other weather. The term includes dirt, sand, gravel, refuse, and wood chips but excludes an agricultural product in its natural state.
(3) "Motor vehicle" has the meaning assigned by Section 621.001.
(4) "Public highway" includes a public road or street.
(4-a) "Refuse" means trash, rubbish, garbage, or any other discarded material.
(5) "Semitrailer" has the meaning assigned by Section 621.001.
(6) "Trailer" has the meaning assigned by Section 621.001.
(7) "Vehicle" has the meaning assigned by Section 621.001.