Before revision: Historically, the term "sideman" referred to a musician hired to perform live by a band or orchestra leader, a solo artist, or a jointly-owned band with an established membership (for example, a rock band).
After revision: Historically, the term "sideman" referred to a musician hired to perform live by a band (or orchestra) leader, a solo artist, or a jointly-owned band with an established membership (for example, a rock band).