An R-V Connector is a type of electrical connector used to connect an RV, or recreational vehicle, to an external power source. It is also known as an RV power plug or an RV power outlet. The STU in this crossword solution stands for 'standard trailer unit, ' which is the most common type of R-V Connector. This type of connector is typically found on the back of an RV and is used to provide power to the vehicle.