Actually, I quite hate the term “classical.” It refers to a mostly inferior period of music (1750-1825) in which the unbridled invention, experimentation and complicated structures such as fugues, canons, concerto grossi etc. of the Baroque Period (1600-1750) were generally scrapped for a marketable, formulaic, dispassionate style that was so derivative as to be sickening. Thankfully, the period gave birth or improved musical grouping and use of more and larger instruments in composition styles which are still composed today e.g. the symphony, the string quartet, the concerto, and the sonata.
Anyhow, these days, when people think of classical music, it seems to encompass everything, from Renaissance pieces, through the Baroque and Classical periods, even the Romantic (1825-1900) and 20th Century works for orchestra seem to be included. Living composers like Philip Glass, John Corigliano, even John Williams, Hans Zimmer, and Joe Hisaishi get grouped into the mass. So, more so for purposes of general understanding than for accuracy do I call this category “Classical.”
“Art Music” would be my favorite term for it but a friend mentioned to me once that the category “Art Music” sounds like a telephone’s ringing and a toilet’s flushing which isn’t quite what I hoped to convey.