Question

Read this sentence from "The Cask of Amontillado" by Edgar Allan Poe: In painting and gemmary, Fortunato, like his countrymen, was a quack, but in the matter of old wines he was sincere. What does the word quack likely mean?

Answer 1

A person who dishonestly claims to have special talent or skill in a certain area.

Answer 2

The meaning of the word "quack" in this sentence from Poe's  "The Cask of Amontillado" most likely means: "a person who dishonestly pretends to have skills or knowledge."

He seems to be using it as a synonym of "charlatan," since he contrast Fortunato's true knowledge of wines with his pretended expertise on painting and gemmary.