What is "permanent waves"

n. (plural of permanent wave English)

Permanent Waves is the seventh studio album by Canadian rock band Rush, released on January 14, 1980. It was recorded at Le Studio in Morin Heights, Quebec, and mixed at Trident Studios in London, UK. Permanent Waves became Rush's first US top five album, hitting #4 on the Billboard 200, and their fifth gold (later platinum) selling album. The album marks a distinct transition from long, conceptual pieces, into a more accessible, radio-friendly style and consequently, a significant increase in record sales for the band. The singles " The Spirit of Radio" and " Freewill" both received significant radio airplay.