How is rap not music?

Although I don't listen to Rap as I mainly listen to Metal, Rap is music whether people like it or not. Rap stands for "Rhythm and Poetry" which is what all genres of music are composed of. So technically all music can be considered Rap but thats besides the point. The defination of music is "an art of sound in time that expresses ideas and emotions in significant forms." In Rap they express their ideas and emotions ,whether it be good or bad, in their music so therefor it is considered music. And this is coming from a headbanger