It's a phrase you frequently hear and what people usually mean by it is, "I don't like the sort of music they play on Classic FM" Wikipedia go into great detail as to what they think Classical music, in the Western tradition, is. Dating back to the dark ages and incorporating the 'classical' period, as opposed to the 'baroque' say.
I think that defining Classical music is much simpler than this. In any given period one supposes, a huge amount of music was created, by every culture and race since time immemorial. Very little has been passed down the generations and has stood the test of time. From Bach's Baroque to African Bantu Drum Music, if it has stood the test of time, then it's Classical, if it hasn't, then it isn't.
So the interesting question then is what music from from the period just after the 2nd War to today will be remembered and deemed Classical in 1000 years time. It's impossible to know as we will be safely dead, but I doubt very much it will be the experimental caterwailing that passes for contemporary experimental classical music, nor the formless meandering jazz explorations, that Jazz buffs are so fond of.
I'd put money on the names of Pink Floyd, Dr Dre, Kraftwerk, Ennio Moriconnie, Hans Zimmer and the Beach Boys, appearing..
...and not The Beatles, The Rolling Stones, David Bowie, Andrew Lloyd Webber, Elton John nor Michael Jackson regardless of how those artists are perceived today.
