I thought you might be interested in the following definition of "noir." This quote comes from an article in Publishers Weekly in which Dennis Lehane and Eddie Muller, two bestselling thriller writers (who specialize in noir), discussed the subject.
“Long before we met, I read your work on noir and taught your book,” [Dennis Lehane] told [Eddie] Muller, referring to Dark City: The Lost World of Film Noir. Muller has called noir “working class tragedy,” and Lehane agreed with that assessment.
“In Greek tragedy they fall from great heights,” said Lehane. “In noir they fall from the curb.”
Doesn't that just knock your socks off?
The full article is here: http://www.publishersweekly.com/pw/by-topic/book-news/page-to-screen/article/48437-dennis-lehane-talks-noir-politics-and-how-clint-eastwood-sounds-on-the-phone.html