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®

superfluous
     adj 1: serving no useful purpose; having no excuse for being;
            "otiose lines in a play"; "advice is wasted words"
            [syn: {otiose}, {pointless}, {wasted}]
     2: more than is needed, desired, or required; "trying to lose
        excess weight"; "found some extra change lying on the
        dresser"; "yet another book on heraldry might be thought
        redundant"; "skills made redundant by technological
        advance"; "sleeping in the spare room"; "supernumerary
        ornamentation"; "it was supererogatory of her to gloat";
        "delete superfluous (or unnecessary) words"; "extra ribs
        as well as other supernumerary internal parts"; "surplus
        cheese distributed to the needy" [syn: {excess}, {extra},
        {redundant}, {spare}, {supererogatory}, {supernumerary}, {surplus}]