Rock music of Canada the 1920s, rock and roll did not acquire its name until the 1950s. "Rock"' or its forerunners electric blues (Chicago blues) and rhythm and blues (Jump blues) was first heard in the late 1940s by Canadians who were living close enough to the American border to tune into American radio station broadcasts. In 1951, Cleveland, Ohio, disc jockey Alan Freed began playing rhythm and blues music for a multi-racial audience, and is credited with first using the phrase "rock and roll" to describe the musical sound of the Doo-wop vocal groups and the rockabilly singers who emerged in the 1950s.
Rock and roll backbeat, that are now more commonly called simply "rock music" or "rock". The term "rock and roll" now has at least two different meanings, both in common usage. The "American Heritage Dictionary" and the "Merriam-Webster Dictionary" both define rock and roll as synonymous with rock music. "Encyclopædia Britannica", on the other hand, regards it as the music that originated in the mid-1950s and later developed "into the more encompassing international style known as rock music". The phrase "rocking and rolling" originally described the movement of a ship on the ocean, but was used by the early twentieth century, both to