That's what the losing side considered. The winning side considered it a civil war and the winners write the history.
Absolutely. Words have no meaning. If the winning side had said, "we are no longer 'Yankees,' we are '@ss clowns,' that would make just as much sense.
Actually when I was in high school (class of '64) and earlier, it was called "The War Between the States." I think Civil War has only recently gained the upper hand.
ML/NJ