The term 'R-V Hookup' refers to a connection between an RV (recreational vehicle) and a power source, such as an electrical outlet or generator. The crossword solutions for this term are STU, which stands for 'Service, Temporary, and Utility.' Service hookups provide access to water, sewer, and electricity, while temporary hookups are designed for short-term use and provide only electricity. Utility hookups are used to connect to a generator and provide electricity.