The definition of Neptune is the eighth planet from the Sun.
An example of Neptune is a planet with regular winds of around 750mph.
See Neptune in Webster's New World College Dictionary
Origin: ModLthe fourth largest planet of the solar system and normally the eighth in distance from the sun: it has a thin, icy ring system around its equator: diameter, c. 49,530 km (c. 30,780 mi); period of revolution, 164.79 earth years; period of rotation, 16.11 hours; 13 satellites; symbol, ♆
Origin: ME < L Neptunus, prob. < IE *nebhtus < base *nebh-, moist > nebula
See Neptune in American Heritage Dictionary 4
Origin: Latin Neptūnus.
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