a book, play, or film that is important and has been admired for a long time:
'La Grande Illusion' is one of the classics of French cinema.
all-time/modern/design etc classic
The play has become an American classic.
something that is very good and one of the best examples of its kind:
What makes a car a classic?
the language, literature, and history of Ancient Rome and Greece [↪ classicist]:
Judith studied classics at Oxford.