Typically defined as a scientist who can allegedly convert any everyday object into gold, the more modern definition is as follows:
Alchemist: The leader, or head man/woman of the under-aged, underground alcohol trade. One who is able to turn money into alcohol through the networking of older non law-abiding citizens who will buy liquor and beer for younger affluent teenagers. Instead of being able to turn objects into gold, he/she can turn money into alcohol aka the gold of the youth.
Girl: "Hey Brad, would you pick me up a 5th of Malibu rum?"
Alchemist: "Why, of course, I can have that for you in 2 hours. I just need the cash."
Girl: "Of course, here is 20 dollars."