What is Rap?

The first major question that I need to identify and term that I need to define is "Rap" (which, in this case, also incorporates the term "Hip-Hop").  Where exactly does the term come from? 

Rap, denotatively, means: a quick blow, the sound produced by such a blow, a talk or discussion 

Although these are merely a few of the multiple meanings of the term, I definitely had one idea that I thought correlated between this definition and the actual music itself. 

If you think in terms of rap as a quick blow and use this "blow" as a metaphorical idea of singing into a microphone.  Then, "the sound" produced almost becomes not the actual lyrics but the beat behind the blow.  When many rappers are actually creating a song, they utilize the beat's rhythm and make sure that it is in time with their lyrics.  Then the production of a "blow" and its "sound" is produced.  

Rap, under the denotative meaning, also reinforces the idea that it is lyrical fighting.  Although this fighting has occurred physically at some points, it still is a type of lyrical fighting.  Thus, the definition of the term reflects somewhat the connotations of the term.  (Which starts to question which is first connotations or denotations. . . but that is for another time)