Who is credited with coining the term rock n roll?

There are several explanations for this term. One is from blues music (the expression was a euphemism for sexual relations); another is from military aircraft slang. It is difficult to know which one is correct: we know that in music, Cleveland disc jockey Alan Freed is widely credited with making the expression popular, but he did not invent it. Here are several answers given by our contributors:

(1) Word origin of "Rock n' Roll".

Returning World War II aircraft engine mechanics coined the term, 'rock 'n' roll". Since most military aircraft engines of this time had a part called a "rocker arm" that had a roller attached to one or both ends to open and close the intake and exhaust valves of an engine, and that this part could be seen when the engine was running with the "rocker arm cover" removed, the mechanics could see this part: "rocking and rolling". An engine that was running well was said to be, "rockin an' rollin". In the 1940's, when the mechanics had leave and could find a place to drink and dance, those G.I.'s who could dance fast and well were said to be able to "rock and roll", just like the fast operating engine part that they were all so familiar with. When these GI's came home at the wars end, they brought the term with them and applied it to the new music that combined Country music, Popular and Western Swing with Rhythm and Blues. The term "Rock 'n Roll" was born from aircraft engines, greasy hands and talented feet from those who survived the war.

(2) Another Explanation

DJ Alan Freed the self-styled "Moondog,"coined the term "rock 'n' roll." Although Alan Freed is widely given credit for coming up with the term "Rock 'n Roll" in the early 1950s, it was already being used in blues songs for several decades, as a euphemistic way of talking about sex. In 1922, Trixie Smith sang "My baby rocks me with a steady roll." Other examples include "Rockin & Rollin Mamma" in 1939; there was also a Buddy Jones song "I love the way you rock & roll," used in the 1944 Arthur Crudup song "Rock me Mamma"; and in a 1946 review of a record, Billboard magazine used the term. Alan Freed as well country-rock performer Bill Haley, certainly helped to disseminate the term when rock music was in its infancy in the early-to-mid 1950s.