Rock-and-Roll (räk'n roll') n. first so used (1951) by Alan Freed, Cleveland disc jockey, taken from the song "My Baby Rocks Me with a Steady Roll". The use of rock, roll, rock and roll, etc., with reference to sexual intercourse, is traditional in blues, a form of popular music that evolved in the 1950's from rhythm and blues, characterized by the use of electric guitars, a strong rhythm with an accent on the offbeat, and youth-oriented lyrics.

rock 'n' roll
n : 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."