Source : Webster's Revised Unabridged Dictionary (1913)

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.

         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.

   Syn: Unnecessary; useless; exuberant; excessive; redundant;
        needless. -- {Su*per"flu*ous*ly}, adv. --
        {Su*per"flu*ous*ness}, n.

Source : WordNet®

superfluously
     adv : in a superfluous manner; "superfluously, he added his silly
           comments to the discussion"