Denotation is defined as the strict dictionary meaning of a word, while connotation is the emotional and imaginative association surrounding a word. In regards to the title of Poe's short story "The Cask of Amontillado," the reader connote that death will be addressed throughout the story. The denotation of the word "cask" is one which means a barrel-shaped vessel that contains liquids. However, the connotation of the word "cask" is associated with the word "casket," which relates to the theme of death throughout the story.

Amontillado is literally an alcoholic beverage, but the connotation gives the reader a feeling that it is rare, foreign, and expensive. Overall, the denotative meaning of the story's title is literally a barrel of wine, while the connotative meaning suggests that the story involves death and is associated with characters hailing from the upper class of society.

In regards to the conclusion of the story, Montresor enacts his revenge by successfully burying Fortunato alive in his catacombs. I find it significant that Montresor mentions that his "heart grew sick" as he placed the last stone in place but says that it was the dampness of the catacombs that made it so. Also, the fact that he hasn't told anyone about the murder in over fifty years suggests that his actions have haunted his mind for some time. These two significant pieces of information indicate that his revenge has taken a toll on his conscience and tortured his soul for a long time, which makes his story a cautionary tale concerning the negative impact of revenge on the mind.

To answer this question, one must understand what denotation and connotation are.  Denotation is the literal or "dictionary" meaning of a word.  Connotation is the emotional or subjective meaning of a word.  For example, one can look up the definition of the word spider and find the literal definition (eight legs, arachnid, etc.).  However, if one would ask me to define the word spider, I might say that it is a scary, creepy, eight-legged creature LOL!  Connotations of words are different for different people.

The literal meaning of the story is that Montresor had a grievance against Fortunato.  He hatches a plan to exact revenge and lures Fortunato to the wine cellar, where he gets him drunk and bricks him up, leaving him to die there.

The connotative meaning is different for different people, obviously.  The connotative meaning for me is that Montresor exacted revenge on Fortunato that is not warranted, mainly because we do not know what, if anything, Fortunato did to upset Montresor.  Also, revenge is never healthy and only causes grief for anyone involved in it.  It does not solve problems between people.  It only exacerbates them.