classical

/ˈklæsɪkl̩/

Of or relating to the first class or rank, especially in literature or art.
Of or pertaining to established principles in a discipline.
(music) Describing European music and musicians of the late 18th and early 19th centuries.
(informal) Describing art music (rather than pop, jazz, blues, etc), especially when played using instruments of the orchestra.
Of or pertaining to the ancient Greeks and Romans, especially 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.
Conforming to the best authority in literature and art; chaste; pure; refined
(physics) Pertaining to models of physical laws that do not take quantum or relativistic effects into account; Newtonian or Maxwellian.

Derived from Latin classicus (especially the highest, relating to the classes of Roman citizenry, of the class).

Latin

classicus

especially the highest, relating to the classes of Roman citizenry, of the class