Analysis: What's Up With the Title?
Okay, not much to work with here—right? "The Purloined Letter." Can't get much more basic than that: the story is about a letter that's been purloined. Case closed.
Well, let's see if we can wrestle something a little more interesting from it. "Purloined," basically means, "stolen." The Oxford English Dictionary's definition for "purloin" is more precise:
2. a. To make away with, misappropriate; to steal, esp. under circumstances which involve a breach of trust; to pilfer, filch. Now freq. humorous, and usually referring to petty theft.
Check it out: "esp. under circumstances which involve a breach of trust." The letter gets purloined twice in the story, and both times involving a definite breach of trust. The first time, sure, D— purloins it from the royal lady. Since he's a minister, that's a definite breach of trust. But the second time involves a breach of trust, too. G— is apparently a friend of D—'s. D— has no reason to suspect G— of deceptive behavior.
What the title does, then, is shift attention from the content of the letter to the method of its purloining. This story is all style, no substance. That lack of content—the lack at the heart of the letter—has gotten a lot of smart people worked up over the years. Here's what two of them had to say:
Majorly smart dude #1 Jaques Lacan wrote a famous (and famously difficult) essay about this story. He says that "purloined" is a version of the word "prolonged," and that "we are quite simply dealing with a letter which has been diverted from its path; one whose course has been prolonged" (source). In other words, the royal lady's letter is off-course. So, maybe the title tells us to read "The Purloined Letter" as the story of the "prolonged" letter trying to get back to its owner.
John T. Irwin, smart dude #2, throws out a related idea: he says the word "purloined" makes it seem like the letter can be stolen, and re-stolen, for all eternity (source). We never see the letter make it back to the royal lady; we only have G—'s word that he'll bring it back. Maybe D— steals the letter again; Maybe Dupin gets it back. Maybe a third miscreant gets the letter. Maybe G— decides to get a little piece of the blackmail action.
The point is, we don't know. The title emphasizes that the most important thing about the letter is its quality of being stolen. Once off course, maybe it's doomed to travel around endlessly—like a ghost ship sailing around forever with a bunch of skeletal pirates.