The word classical has several meanings. In general, these meanings refer to some past time, works of that era or later works influenced by that time. Classical things are often seen as ordered and part of high culture

High culture

High culture is a term, now used in a number of different ways in academic discourse, whose most common meaning is the set of cultural products, mainly in the arts, held in the highest esteem by a culture...

 or a golden age

Golden Age (metaphor)

A golden age is a period in a field of endeavour when great tasks were accomplished. The term originated from early Greek and Roman poets who used to refer to a time when mankind lived in a better time and was pure .-Golden Age in society:...

, and contrasted to earlier or later things which may be seen as chaotic, elaborate or emotional.
The word classical comes from the Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 word classicus, which is similar in meaning to the English phrase first class.