What does "superfluous" mean?

Superfluous: More than is wanted or is sufficient; rendered unnecessary by superabundance; unnecessary; useless; excessive; as, a superfluous price. Shak. An authority which makes all further argument or illustration superfluous. E. Everett. Superfluous interval (Mus.), an interval that exceeds a major or perfect interval by a semitone. -- Su*per"flu*ous*ly, adv. -- Su*per"flu*ous*ness, n.