Wiktionary
n. 1 country music produced some time ago, typically before the early 1990s. 2 traditional country music.
Wikipedia
Classic country is a music radio format that specializes in playing mainstream country and western music hits from past decades.
The classic country format can actually be further divided into two formats. The first specializes in hits from the 1920s through the early 1970s (thus including music that is older than almost any other radio format in the United States), and focus primarily on innovators and artists from country music's Golden Age (including Hank Williams, George Jones and Johnny Cash). The other focuses on hits from the 1960s (including some the above-mentioned performers) through early 1990s, some pre-1960 music, latter-day Golden Age stars and innovators such as Waylon Jennings, Willie Nelson and Merle Haggard) to newer recurrent hits from current-day artists such as George Strait, Garth Brooks, Alan Jackson and Reba McEntire.