Montresor opens Poe's short story "The Cask of Amontillado" by speaking of his desire to revenge some unknown insult to him by Fortuanato. He lures Fortuanato into his wine cellar by telling him of this wonderful wine that Fortuanato must sample. As they go deeper and deeper underground Montresor and Fortuanato continue a conversation. Finally when they get to the part of the cellar that Montresor has prepared he seals Fortuanato up into a wall. The irony of the name Fortuanato is that the name itself means fortune. When we think of fortune we think of riches and good fortune. Through the imprisonment of Fortuanato into the wall and his impending death it is ironic that the character's name fortells of his bad fortune in following Montresor into the wine cellar.
As said before, Fortunato was imprisoned after being lured by the mere thought of Amantillado. So he is not so fortunate like his name suggests.