Origins
The word 'supernova' was coined in 1934 by the astronomers Walter Baade (German-American) and Fritz Zwicky (Swiss-American) at the California Institute of Technology. They combined the Latin prefix 'super-' (above, beyond, exceedingly) with 'nova,' the established astronomical term for a star that suddenly brightens dramatically. 'Nova' is short for Latin 'nova stella' (new star), from 'novus' (new), descending from PIE *newo- (new). The compound 'supernova' thus means literally 'beyond-new' or 'super-new' — a new star that is extraordinarily, transcendently new.
The term 'nova stella' has a distinguished history. When the Danish astronomer Tycho Brahe observed a brilliant new star in the constellation Cassiopeia in November 1572, he titled his published account 'De Nova Stella' (On the New Star). This was a revolutionary observation: Aristotelian cosmology held that the celestial sphere was perfect and unchanging, and the appearance of a new star challenged that doctrine directly. Brahe's 'nova' demonstrated that the heavens were mutable — that new things could appear where nothing had been before. The term stuck, and 'nova' became the standard astronomical designation for a star that temporarily increases in brightness.
Baade and Zwicky's contribution was to recognize that not all novae are the same. Some stellar brightenings are relatively modest — a white dwarf accreting material from a companion star until its surface ignites in a thermonuclear flash. These are classical novae. But the events they studied were orders of magnitude more energetic: the complete gravitational collapse and explosive disruption of a massive star at the end of its nuclear fuel cycle. These catastrophic events release as much energy in a few weeks as the Sun will produce in its entire ten-billion-year lifetime. The prefix 'super-' was necessary to distinguish this cosmic catastrophe from the more modest classical nova.
Proto-Indo-European Roots
The PIE root *newo- (new) is one of the most stable words in the Indo-European family. English 'new' (from Old English 'niwe,' from Proto-Germanic *neujaz), Latin 'novus' (giving 'novel,' 'novelty,' 'renovate,' 'innovate'), Greek 'neos' (giving 'neo-,' 'neon,' 'neophyte'), Sanskrit 'nava,' Russian 'novyy,' and Welsh 'newydd' all descend from the same PIE original. The word has been in continuous use for at least six thousand years, making it one of humanity's oldest surviving vocabulary items.
The irony of naming a stellar death 'new' was noted even by early astronomers. What appears to terrestrial observers as a 'new star' is in fact the death of a very old one — a star that burned for millions or billions of years before exhausting its nuclear fuel and collapsing. The 'newness' is a function of human perspective: the explosion happened long ago and far away, and the light has only just reached us, creating the illusion of sudden appearance. The word 'supernova' thus preserves a pre-scientific misconception — the belief that these events represent births rather than deaths — in its very structure.
Supernovae are among the most important events in cosmic history. The heavy elements that compose the Earth and all living things — iron, gold, uranium, carbon, oxygen — were forged in the nuclear furnaces of massive stars and dispersed through the galaxy by supernova explosions. The calcium in your bones, the iron in your blood, the carbon in your DNA were all created inside stars that later exploded. In a sense that is both poetic and literally true, human beings are made of supernova debris. The word 'supernova' — 'beyond-new' — is thus more apt than its coiners intended: each supernova creates the raw materials from which genuinely new things — planets, oceans, organisms — will eventually be made.
Legacy
Historical supernovae have been recorded by human observers on several occasions. The supernova of 1054 CE, which produced the Crab Nebula, was recorded by Chinese and possibly Arab astronomers. Tycho's supernova of 1572 and Kepler's supernova of 1604 were observed in Europe. No supernova in our own galaxy has been observed since Kepler's, though supernovae in other galaxies are detected regularly by modern telescopes. The next galactic supernova, when it occurs, will be visible to the naked eye and will provide an unprecedented opportunity for multi-wavelength observation — a 'new star' that will vindicate, once more, the ancient and misleading name.