Bill Monroe was the first performer to bring the virtuosic side of country music to the general public. His instrumentation of fiddle, mandolin, banjo, guitar, and string bass performed rhythmically tight virtuosic music, more reminiscent of jazz than of anything that had been heard in country music before. What genre was his music labeled

The genre of Bill Monroe's Music is known as Bluegrass genre.

Bluegrass genre is a musical style that originated in the 1940 in Appalachian portion of the United States.

The Bluegrass genre of music is a tradition-based modern style of string band music.

Usually, the bluegrass genre of musics consists of 4 to 7 performers who sing while playing on acoustic string instruments like guitar, double bass, fiddle, mandolin, steel guitar etc.

Therefore, the genre of Bill Monroe's Music is known as Bluegrass genre.

Learn more about the Bluegrass genre here

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"Bluegrass" genre was his music labeled.

Explanation:

An American heritage musical style that originated in the Appalachian portion of the United States throughout the 1940's is titled as "Bluegrass Music". The artists band like Bill Monroe and the Blue Grass Boys derived its title from such genre. This style  has origins in traditional British, Scotland and Irish ballads and dance songs, and also rooted from blues and jazz of African-American. There are 3 significant Bluegrass subgenres: