The American Heritage® Dictionary of the English Language, 4th Edition
n. A rare celestial phenomenon involving the explosion of most of the material in a star, resulting in an extremely bright, short-lived object that emits vast amounts of energy.
n. A star which explodes, increasing its brightness to typically a billion times that of our sun, though attenuated by the great distance from our sun. Some leave only debris (Type I); others fade to invisibility as neutron stars (Type II).
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a star that explodes and becomes extremely luminous in the process
Word Usage
"To describe her, she said, don't use the word supernova."