Well,it's at least in a three-way tie with Euro-Pop and Rap. MY description of jazz is "all technique,no tune",but probably the best description I ever heard was in the movie "The Commitments". They had been on stage playing something like a Percy Sledge song,and the trumphet player got "creative". When the set was over the lead singer asked him what the hell that was all about,and he replied,"I thought I would jazz it up a little". The singer's reply is a classic. He said "You know what jazz is don't you? It's musical mastrubation!"