A hole in the septum (the cartilage divider between both halves of the nose) that can result from heavy cocaine use.
Ask Rob to show you his third nostril. He can put a rolled up kleenex in one side and pull it out the other, and floss it back and forth. It's nasty as shit.
by Buster the Cat April 14, 2011
1 more definition
Head shots in FPS games
"Woah! I gave him a third nostril!"
by ZionMunkee December 03, 2006