Modifies a noun

• music: Hillbilly music: Songs written by Arkansas composer William Hill.

• rock: Their self styled brand of hillbilly kung-fu funk rock has been attracting national attention, with plays on XFM.

• heroin: The thing that's amazing was how rapidly he went from smoking pot to doing hillbilly heroin.

• heaven: Listen to Johnson's high keening and primitive vocal style influenced by Bill Monroe and go straight to hillbilly heaven.