The term 'ROCK MUSICAL' can be broken down into two crossword solutions: HAIR (4 letters). HAIR is a rock musical written by James Rado and Gerome Ragni, which debuted on Broadway in 1968. It tells the story of a group of hippies living in New York City during the Vietnam War era, and their struggles with identity, drugs, and war. The musical was made into a movie in 1979, and has since become a cult classic.