Is bowls an american term for the cone of a bong or is it the bowl you mix a mull in...
The term "bowl" usually means a bowl-full (the bowl is the little piece that holds your weed and where you light it), a fully packed bowl of weed. So if someone says they smoked four bowls, that means they had four bowl-fulls. It's quite a universal term, works for bongs and pipes (pipes are also referred to as just bowls--such as a glass bowl)