Merriam-Webster defines it as "adjective: of or resembling the fictional detective Sherlock Holmes especially in the exercise of unusual powers of deduction."
Google's primary source says, "adjective: relating to or characteristic of Sherlock Holmes, especially in showing great perceptiveness" as well as "noun, informal: a fan of the Sherlock Holmes detective stories by Sir Arthur Conan Doyle."
There we go. "A fan of Sherlock Holmes."
Yet for the entirety of my forty-plus years as a Sherlockian, there have been those who insist that while they are a Sherlockian, they are not a fan. They're an enthusiast. Or an aficionado. Or something else far too scholarly to be called merely "fan." And yet fans there are, or else why are they focusing on this single subject? How are they attracted to it without being fans? Some cold, machine-like logic that mathematically directs them toward the study of Sherlock Holmes?
C'mon, you sillies. You're fans.
Since a certain Eminem song has come out fans have a new way to elevate themselves above the worst of our lot. Now instead of going all "aficionado" we can just single out those misbehaving fans as "stans." (Definition, for those who don't know: "an overzealous or obsessive fan of a particular celebrity.") Some of us might freely self-identify as stanning for Sherlock Holmes, but for the rest, that term is always there for that "Jeez, I'm not that bad!" moment.
Can a doctor be a fan? Yes. Can a lawyer be a fan? Yes. Can a literature professor be a fan? Yes.
No matter how serious or learned you may be in one aspect of your professional life, you have to do something for entertainment, and unless your Sherlockian activities account for 100% of your sole, sustaining income, there must be a fan in there somewhere. But, of course, here in America, we know one thing -- anything English is fancy, and Sherlock Holmes, therefore, is a fancier's hobby. (At least here in the U.S., you folk of other nations can speak for yourselves.) We can sip our hot tea, listen to Vivaldi, and dramatically turn the page of our leather-bound Literary Fancier's edition of The Hound of the Baskervilles. The aficionado is a sort of role-play, really, just as the wine connoisseur is something of a role as well. Remember the days when beer drinkers were common folk? They got fancy on us, too.
Fans can be Stans, and Stans can be Fancy Dans. And that's okay. Fancy without going "true fan" or gatekeeper can be pretty cool. We all get to play our own game our own way. And since the origin of the word "fancy" is as a contraction of the word "fantasy," it fits most of the creations of the fan, being all fancy like that.
And we all should be able to fancy that, even the least fan-sy of us.