I didn’t know, however, just how “fanboy” entered the language in the first place. It’s an interesting story, but you won’t find it in the dictionary. The word is there–in fact, when Merriam-Webster added it in 2008, numerous celebratory news stories marked the fact.
But everybody was so tickled that they failed to notice that Merriam-Webster’s definition stunk. A fanboy, that dictionary says, is “a boy who is an enthusiastic devotee (as of comics or movies).” As anyone who’s either been called a fanboy or called someone else one knows, the boy part isn’t a reference to youth. More often, it’s a taunt, suggesting that the person in question is goofy and childish. Fanboys come in all ages, and fanboyism isn’t the exclusive preserve of males.
Merriam-Webster’s entry says that “fanboy” dates to 1919–the same year specified by the Oxford English Dictionary, which quotes a newspaper’s reference to baseball “fan boys.” The second reference to fanboys identified by the OED occurred in 1985.
(read the rest of this fascinating lexographical usage at the link below)