A lot of films are also called Film-Noirs on IMDB for no reason other then the fact they aren't westerns or musicals. I think it's become a little overused. Double Indemnity is the best, and definitive film-noir IMO.

After the 50's, it became Neo-Noirs, and the closest a Neo-noir ever came to the original film-noirs IMO, was Polanski's masterpiece Chinatown.