Meganova

A meganova was a stellar event presumably greater than a supernova.

When the Sixth Doctor recognised Ostrecallis Mediosai on the planet Strellin, he recounted that it was originally native to Ostrecallis Major and supposedly went extinct when the entire Ostrecallis system was consumed by a meganova, wondering if the seeds were driven by solar winds to drift through space.

Assessor Pendle of the Galactic Census Bureau was unfamiliar with the term "meganova". (AUDIO: Order of the Daleks)