What is a semitrailer?

A semitrailer is defined as a type of trailer that is designed to rest on or be carried by a truck or truck tractor. This design allows a portion of the semitrailer's weight to be supported by the truck or tractor to which it is attached, contributing to stability and load distribution during transport. The coupling mechanism, typically a fifth wheel, connects the semitrailer to the towing vehicle, allowing for mobility while maintaining a significant portion of the trailer's weight on the tractor.

In contrast, a trailer designed to carry passengers does not apply to semitrailers since they are primarily cargo carriers. A vehicle that operates independently of a truck would refer to a different type of vehicle entirely, such as a standalone trailer, which does not align with the characteristics of a semitrailer intended for transport with a truck. Lastly, a trailer used exclusively for agricultural purposes would also not be a semitrailer as it does not define the standard configuration or intended use which is primarily for freight transportation and not restricted to agricultural applications.