* A builder: This is the literal meaning of the word, referring to a person who works with stone and mortar. Montresor uses this meaning when describing his own lineage and his family's history of building.
* A member of the Freemasons: This is a secret society known for its elaborate rituals and symbols. Montresor uses this meaning to taunt Fortunato, suggesting that he is not a true mason because he lacks the qualities of a good Freemason, such as honesty, loyalty, and brotherly love.
The pun is established through the following conversation:
* Montresor: "You are not a Mason?"
* Fortunato: "Yes, I am."
* Montresor: "You? Why, no; you are not a Mason."
* Fortunato: "Yes, yes; I am a Mason."
* Montresor: "You? You may be a Mason in name, but you are not a Mason in heart."
Montresor mocks Fortunato by implying that he is not a true "Mason" because of his flaws and his inability to recognize Montresor's true intentions. This pun highlights the irony of the situation: Montresor, who claims to be a true "Mason," is actually going to betray Fortunato, a fellow "Mason," in a brutal act of revenge.