"Film Noir"

Film Noir is a genre that falls within the lines of a detective or crime story. It has a more gloomy and downbeat setting. The term itself was thought up by French film critics.

...Very often, a film noir story was developed around a cynical, hard-hearted, disillusioned male character who encountered a beautiful but promiscuous, amoral, double-dealing and seductive femme fatale..."

I hope this following link will better your understanding of what "film noir" really means, I know it helped me.