[Z]

I don't think there's any real definition of a "chav" to be honest, my general rule is that if I'm walking past someone or a group of two or three people, and they look threatening enough that I feel the need to cross the road because of the way they are walking, the way they dress or that they're carrying alcohol on them in the street - they're probably a chav. Obviously with a large group of people you tend to feel intimidated anyway, regardless of who's actually in the large group.