Double Entendre: A double entendre is a literary device in which a word or phrase is used which can be interpreted two different ways. The first definition of the word or phrase is typically straightforward while the second definition is usually ironic or inappropriate. Poe utilizes double entendres a couple of times throughout the short story.
When Montresor and Fortunato are walking through the catacombs, Montresor encourages him to turn around because of his health, and says, "You are a man to be missed" (Poe, 3). This phrase has two meanings. The first meaning is that people will literally miss Fortunato's company while he walks through the vaults, and the second meaning is that people will miss him because he will never return from the catacombs.
Later on, when Fortunato says that Montresor is not a mason, he replies, "Yes, yes . . . yes, yes" (3). Montresor's affirmative answer has as an ominous double meaning. Montresor proceeds to show Fortunato a trowel, which indicates that Montresor actually meant that he is a mason, which implies that he will build a wall around Fortunato.
Simile: A simile is when two different things are compared using the words "like" or "as." While Montresor and Fortunato are walking through the catacombs, Montresor uses a simile to describe the appearance of the nitre on the walls of the vaults. Montresor says, "The nitre! . . . see, it increases. It hangs like moss upon the vaults" (5).