1. A permanent marker, especially a black one. Based on the trademark for a brand of permanent marker that has become synonymous with this style of marker. Would you pass me a sharpie? I need to label these boxes. She used a sharpie to sign the documents, and the ink bled through to all the papers beneath.

2. A cheat, swindler, or fraudster; a sharper. That sharpie promised us a huge payout but ended up running off with all our money! She made a living as a card sharpie, using sleight of hand to win money off unsuspecting gamblers.

3. A very intelligent, quick-witted, alert person; someone who is very sharp. They hired a real sharpie to take over the case. Now it's looking very likely that they'll win. Tom has tended to date pretty dull guys over the years, so it's nice to see him with a sharpie for a change!