The Collaborative International Dictionary of English v.0.48:

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]