noun

• (colloquial) An alert person.
  "Eunice Marshall asked in a bored tone, "Are you, by any chance, selling magazines?" Daisy grinned childishly, enjoying Eunice's mistake. "You're quite a sharpie, aren't you, ma'am? You figured me out a whole lot faster than most people do.""
• (US, regional) A knowledgeable fisherman.
  "1976 December, Ken Schultz, Field & Stream Fishing Contest Winners: Nothing but the Best, Field & Stream, page 78, Eventually DeBlasio became a sharpie. In New York and New Jersey coastal fishing parlance a “sharpie” is one who fishes seven days a week all summer long, selling his fish to the market to make a living. Sharpies supposedly have fishing down to a science, to such a degree that they only go to particular places, at particular times, using particular fishing methods, and come back with a boatload of fish while everyone else wonders in amazement."
• (US) A swindler.
  "Three booths down a couple of sharpies were selling each other pieces of Twentieth Century Fox, using double arm gestures instead of money."
• (US) A long, narrow fishing boat used in shallow waters.
  "He brought this pair of sharpies, the Lucia and the Ella, to Beaufort by schooner and began to use them for fishing, oyster dredging, and even as a passenger ferry and party boat. The sharpie is a flat-bottomed, shallow-draft vessel of moderate size, comparable to a sloop or schooner."