Maybe you do not know what the word "rap» («rap») appeared in English in the late 19th century. Originally it meant "speak", "talk».
A little later, "rap" acquired a meaning of "conversational banter", "dispute" ("debate"). In the 70s of the 20th century to "rap" come to "an improvised performance poetry", which, in turn, acquired a modern look, "rap" - a type of music with a rhythmic performance of spoken text.
via factroom.ru