Final answer:
A device that connects a trailer to a trailer hitch is called a trailer coupler. This coupler attaches to the trailer tongue and latches onto the hitch ball, featuring safety mechanisms to ensure a stable and secure connection.
Step-by-step explanation:
A device that ensures the connection of a trailer to a trailer hitch is called a trailer coupler. The trailer coupler is attached to the trailer's tongue and it latches on to the ball of the hitch on the towing vehicle, securing a stable link. It's critical that a coupler is properly sized and compatible with the hitch to ensure safety. Additionally, couplers come with safety mechanisms like locking pins to prevent accidental disconnection during transport.