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Definition of 'nova'

noun

A star that ejects some of its material in the form of a cloud and become more luminous in the process

From: GCIDE

Nova \No"va\ (n[=o]"v[.a]), n.; pl. L. Novae (n[=o]"v[=e]), E. Novas (n[=o]"v[.a]z). [L., fem. sing. of novus new.] (Astron.) A star which suddenly increases in brightness thousands of times, then fades back to near its original intensity. It may appear as a "new" star if its original brightness was too low for routine observation. A star which suddenly increases in brightness to many millions of times its original intensity is a supernova, and the postulated mechanisms for the increases of brightness of novae and supernovae are different.
Note: The most important modern novae are:
{No"va Co*ro"nae Bo`re*a"lis}[1866];
{No"va Cyg"ni}[1876];
{No"va An*dro"me*dae}[1885];
{No"va Au*ri"gae}[1891-92];
{No"va Per"se*i}[1901]. There are two novae called {Nova Persei}. They are: (a) A small nova which appeared in 1881. (b) An extraordinary nova which appeared in Perseus in 1901. It was first sighted on February 22, and for one night (February 23) was the brightest star in the sky. By July it had almost disappeared, after which faint surrounding nebulous masses were discovered, apparently moving radially outward from the star at incredible velocity. [Webster 1913 Suppl. +PJC]