Meaning

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

originFeminine nominative singular of Latin novus (“new”). The feminine is used since stella (“star”) is feminine; thus nova is a shortening of nova stella (“new star”), first used in this sense in 1573 by Tycho Brahe.

Etymology from Wiktionary, CC BY-SA 3.0