What does nevermore mean in the raven?

Now that's a tricky question, One may translate it as the raven being his inner self reminding him that he may never see his love again. Telling him nevermore every time he see allusions or think of her. because in the beginning he heard a knock and thought it was his love. some may say that the raven is a demon telling him that he would never be happy again.

He will never again see Lenore, or get rid of the bird.