First of all, 'JAZZ' is too general a term to be used in any meaningful way. There is as much difference between Dixieland jazz and bebop and avant garde' jazz and jazz funk and jazz fusion and afro-cuban jazz and and and ....the list goes on. There are different rules for each, including non-improvisational jazz where every single note is scripted (think high school jazz band). It sort of fits Henry Miller's description of porn; "you can't define it, but you recognize it when you see it" (or something to that effect). I guess if you can't handily fit a piece of music into ANY OTHER category, then it must be jazz. Here's another definition; if you can't PLAY it or don't understand it, it must be jazz. Here's another; if it's best played by hollow-eyed junkies, it must be jazz (as opposed to 'regular' addicts, in which case it must be ROCK). BTW, if said junkies have been clean and sober for at least three months, then it must be 'Country' or 'Christian contemporary'.

Here is a SURE-FIRE way to know that it ISN'T jazz; and that's if it's played on an arranger .

chas