Where can I locate the definition of the name Montresor? I know there's an article on this website regarding it, but I need to find where the information on the name came from.

Julie Hess wrote a  literary analysis of "The Cask of Amontillado" in 2005 entitled "Poe’s Use of Irony in “The Cask of Amontillado” in which she offers two translations of Montresor's name. Hess's paper can be accessed at the link below.
Hess asserts that the names of the protagonist and antagonist, Montresor and Fortunato, are "different aspects of one personality."  Hess cites an article entitled "Anything Goes: Comic Aspects in ‘The Cask of Amontillado" by John Clendenning published by Gale Group in Short Story Criticism that explains that the name Montresor is a hybrid of the French words montrer (to show) and sort (fate).  In the story, Montresor shows Fortunato his fate: death by entombment as retribution for all the insults and injuries he has inflicted upon Fortunato.
Hess, et al.  also claim that the French words mon (my) and tresor (treasure) are symbolic of Montresor burying his treasure: the body of the man on whom he enacted the ultimate revenge, Fortunato.