Nova

The basic definition of Nova as defined on Wikipedia is: A nova (plural novae) is a cataclysmic nuclear explosion in a star caused by the accretion of hydrogen on to the surface of a white dwarf star, which ignites and starts nuclear fusion in a runaway manner. Novae are not to be confused with supernovae or luminous red novae.

Then of course there are the other definitions with nova being a reference to a novel or as a plural form of novum. However the most interesting definition I saw mentioned  was a star that suddenly becomes thousands of times brighter and then gradually fades to its original intensity. 

This is descriptive of the universe as a whole...but interesting because there are clearly differing levels of initial intensity.