Definition of moonies:
(n) :
(fandom slang) A fan of the Japanese manga and anime franchise Sailor Moon.
(n) :
(informal) A member of the Unification Church; a follower of its founder Sun Myung Moon.
(n) :
(informal) A person who shows exceptional enthusiasm for a cause or organization, a zealot.
(n) :
(informal) A nickname in English-speaking countries, sometimes for a person who moons around.
(n) :
(archaic, Northern England) The European goldcrest.