Somehow I've known about supernovas for many years without realizing that the word and concept "nova" exists as well. It's from the Latin for "new": the appearance of what seems to be a new star, because the star going nova brightened enough to become visible from Earth. (It got picked up from Tycho Brahe describing what we'd now call a supernova, though.)

The mechanism for non-super novas is very interesting: a white dwarf in a binary star system steals hydrogen from the other star, then heats it until it starts to fuse, which blows it all off into space!