The Collaborative International Dictionary of English v.0.48:

Superfluous \Su*per"flu*ous\, a. [L. superfluus overflowing;
   super over, above + fluere to flow. See Super-, and
   Fluent.]
   More than is wanted or is sufficient; rendered unnecessary by
   superabundance; unnecessary; useless; excessive; as, a
   superfluous price. --Shak.
   [1913 Webster]

         An authority which makes all further argument or
         illustration superfluous.                --E. Everett.
   [1913 Webster]

   Superfluous interval (Mus.), an interval that exceeds a
      major or perfect interval by a semitone.
      [1913 Webster]

   Syn: Unnecessary; useless; exuberant; excessive; redundant;
        needless.
        [1913 Webster] -- Su*per"flu*ous*ly, adv. --
        Su*per"flu*ous*ness, n.
        [1913 Webster]