"Rock and roll" (a slang term meaning sexual intercourse believed to have been picked up from black DJ's down south), was applied to the "new" music being enjoyed by young people in the early 50's.
Correct me if I'm wrong, but this thread has got me thinking. It seems like the 50's is what gave rise to musical personalities , ie the kind of band we know now with a marketable lead, with Elvis being one of the firsts to market themselves as part of a new generation. Before that, it seems they were marketed more as ensembles. The whole change seems to go in line with the change in attitude.
