Music:
* I prefer listening to classical music over pop music.
* The concert hall was filled with the sounds of classical piano.
Literature:
* The professor's lecture focused on classical Greek literature.
* Shakespeare's plays are considered classical works of English literature.
Art:
* The museum housed a collection of classical sculptures from Ancient Rome.
* She admired the classical architecture of the building.
Other:
* He was taught using classical educational methods.
* The debate centered around classical economic theory.
Formal:
* The Classical period in music is characterized by its formal structure and emphasis on melody.
Informal:
* I'm not really into classical music, but I do enjoy the occasional Beethoven symphony.
The meaning of "Classical" will depend on the context in which it is used.