What is the legal definition of a trailer?

1. A motor vehicle that is intended to be towed behind a motor vehicle.
2. A motorized trailer with a frontal part resting against the support surface of a towing vehicle.
3. Correct answer: A non-motorized vehicle that is intended to be towed behind a motor vehicle.
4. The legal definitions of a trailer and a semit-trailer are identical.

WhyA trailer is a non-motorized vehicle made to be towed by a motor vehicle. A broken-down car on a tow is not called a trailer.