The Collaborative International Dictionary of English v.0.48:

Excessive \Ex*cess"ive\ ([e^]k*s[e^]s"[i^]v), a. [Cf. F.
   excessif.]
   Characterized by, or exhibiting, excess; overmuch.
   [1913 Webster]

         Excessive grief [is] the enemy to the living. --Shak.

   Syn: Undue; exorbitant; extreme; overmuch; enormous;
        immoderate; monstrous; intemperate; unreasonable. See
        Enormous --Ex*cess*ive*ly, adv. -Ex*cess"ive*ness,
        n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

excessiveness
    n 1: immoderation as a consequence of going beyond sufficient or
         permitted limits [syn: excess, excessiveness,
         inordinateness]

Moby Thesaurus II by Grady Ward, 1.0:

74 Moby Thesaurus words for "excessiveness":
   abandon, bigotry, boundlessness, crapulence, crapulency,
   crapulousness, drunkenness, egregiousness, enormousness,
   exaggeration, excess, exorbitance, exorbitancy, extortionateness,
   extravagance, extravagancy, extreme, extremeness, extremes,
   extremism, extremity, fabulousness, fanaticalness, fanaticism,
   giantism, gigantism, gluttony, hyperbole, hypertrophy, immoderacy,
   immoderateness, immoderation, incontinence, indiscipline,
   indulgence, inordinacy, inordinance, inordinateness, intemperance,
   intemperateness, monstrousness, nimiety, outrageousness,
   overdevelopment, overdoing, overenthusiasm, overgreatness,
   overgrowth, overindulgence, overlargeness, overmuch, overmuchness,
   overreaction, overreligiousness, overzealousness, perfervidness,
   preposterousness, prodigality, rabidness, radicalism,
   self-indulgence, swinishness, too much, too-muchness,
   ultrazealousness, unconscionableness, unconstraint, uncontrol,
   undueness, unreasonableness, unrestrainedness, unrestraint,
   zealotism, zealotry