WordNet (r) 3.0 (2006):

rock music
    n 1: a genre of popular music originating in the 1950s; a blend
         of black rhythm-and-blues with white country-and-western;
         "rock is a generic term for the range of styles that
         evolved out of rock'n'roll." [syn: rock 'n' roll,
         rock'n'roll, rock-and-roll, rock and roll, rock,
         rock music]