Is Kung-Fu a correct term for Chinese Martial Arts?
In Western countries we often use Kung Fu to talk about Chinese martial arts but this is an improper term that should be replaced by Wushu (martial arts). Chinese people also often use Guoshu (national [martial] art), Quanshu (boxing arts), Quanfa (Boxing techniques), Jiji (combat science) or Wugong (martial exercises).
If we use Kung Fu it is because of a Cantonese expression "da gongfu" (cant: Ta Kung Fu) which means practice martial arts. As Cantonese peoples are the biggest Chinese oversee community in western countries, their terminology was widely used. But we must be aware that 30 years ago quite few experts really knew Chinese Wushu in Western countries and they almost never taught to non-Chinese, thus many teachers gathered under the term Kung Fu a variety of techniques borrowed in other even non-Chinese martial arts.
So to resume, Gongfu is not a style of wushu