rock musicn. See rock2.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.rock musicA type of pop music that developed out of rock?n?roll in the 1960s and 1970s. It is based around amplified instruments, especially the electric guitar and electric bass, and is characterized by a strong bass line and driving rhythms. It is typically performed by rock groups, and while fast dance music is the staple form, slower ballad-style songs are also a popular part of the repertoire.Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited