SUV is an acronym for Sport Utility Vehicle, which I think has been forgotten, as the term now extends to vehicles that are neither sport nor utility.
The earliest SUVs were the first Chevrolet Suburban and military-inspired Jeep vehicles. Soon after those we had SUVs from International and Land Rover, then more from Chevy, Jeep and Ford. Those old Scouts and Broncos and Discoverys were true sport utility vehicles, with the power and capability to conquer any road, or lack thereof, put in front of them.
Today we have “compact SUVs” and “crossover SUVs,” which, in every sense of the word, are not SUVs at all.