classic (adj.) Look up classic at Dictionary.com
1610s, "of the highest class; approved as a model," from French classique (17c.), from Latin classicus "relating to the (highest) classes of the Roman people," hence, "superior," from classis (see class). Originally in English, "of the first class;" meaning "belonging to standard authors of Greek and Roman antiquity" is attested from 1620s.
classic (n.) Look up classic at Dictionary.com
"a Greek or Roman writer or work," 1711, from classic (adj.). So, by mid-19c., any work in any context held to have a similar quality or relationship. In classical Latin noun use of classicus meant "a Marine" (miles classicus) from the "military division" sense of classis.