A “virtuoso” is someone with exceptional skill or knowledge in a particular subject, usually relating to the arts. Montresor seems to express anti-Italian sentiment when he claims that few Italians possess genuinely strong skills and instead show “enthusiasm” when it “suit[s] the time and opportunity.” However, he concedes that Fortunato’s knowledge of old wines is indeed virtuosic.
A trowel is a tool masons use to smooth the mortar when laying bricks. Also, a great irony—Fortunato is so intoxicated that he doesn’t even wonder what Montresor is doing with a trowel.
"immolation..."See in text(The Cask of Amontillado)
Poe’s word choice here, “immolation,” indicates something much more than simple murder; rather, it suggests a more spiritual element to Montresor’s revenge with connotations of offering (burning) something as a sacrifice.
"In pace requiescat!..."See in text(The Cask of Amontillado)
These final words (which translate to "rest in peace") are not ironic but completely sincere. Fortunato has been dead for fifty years, and Montresor no longer has any of the ill feelings he had for the man. That, in fact, was the whole purpose of his plot to kill him. He wanted to rid himself of his exceedingly painful inner feelings of resentment and rage. Montresor specified at the beginning that he wanted to achieve the perfect revenge. The last words verify that he has succeeded in doing so to his complete satisfaction. He has created a masterpiece of revenge.
Nitre is another word for the mineral form of potassium nitrate. This mineral is toxic when breathed for extended periods of time or in high concentration. Poe gives Fortunato a severe cold for a purpose, as the nitre makes him cough frequently and keeps him from asking a lot of questions about the Amontillado that Montresor might not be able to answer.
Poe strategically uses this French wine to play on the English phrase “of the grave.” Poe’s careful word choice contributes to the story both literally and figuratively. In this case, we see how this subtle choice foreshadows the characters' destination.
"Nemo me impune lacessit.”..."See in text(The Cask of Amontillado)
This Latin phrase translated to, “No one attacks me with impunity.” This all-too-appropriate motto, along with the lurid coat of arms, are most likely totally fictitious. Montresor may be inventing them for the pleasure of hinting at what he intends to do to Fortunato. Fortunato's response suggests that he doesn't understand Latin and is only pretending to understand the motto.
Rheum is a thick watery discharge from the eyes. Poe uses vivid description in this line to emphasize how intoxicated Fortunato currently is. Notice how Poe continues to use Fortunato’s intoxication to help Montresor set the stage for his revenge.
"roquelaire..."See in text(The Cask of Amontillado)
A roquelaire is an 18th century, knee-length men’s cloak that is worn over the shoulders. Poe juxtaposes Fortunato’s colorful jester’s costume with Montresor’s dark, villainous outfit, turning what could be a macabre story into one that’s slightly humorous.
Poe’s choice to have Fortunato in a jester costume (motley), complete with conical cap with bells, symbolizes Fortunato’s foolishness: he is easily persuaded to follow Montresor and rarely questions him. As Fortunato continues to be tricked, it is only fitting that he look the part.
"progress arrested by the rock..."See in text(The Cask of Amontillado)
This means that Fortunato had come to end of the recess in the granite wall. He had expected to find the Amontillado but had only found the granite wall of the remotest side of the catacombs. The use of "arrested" adds to the ominous mood because of the associations it has with jail and entrapment.