(1):
(n.) Of or pertaining to the ancient Greeks and Romans, esp. to Greek or Roman authors of the highest rank, or of the period when their best literature was produced; of or pertaining to places inhabited by the ancient Greeks and Romans, or rendered famous by their deeds.
(2):
(n.) Conforming to the best authority in literature and art; chaste; pure; refined; as, a classical style.
(3):
(n.) Of or relating to the first class or rank, especially in literature or art.