The Collaborative International Dictionary of English v.0.48:

Immoderate \Im*mod"er*ate\, a. [L. immoderatus; pref. im- not +
   moderatus moderate. See Moderate.]
   Not moderate; exceeding just or usual and suitable bounds;
   excessive; extravagant; unreasonable; as, immoderate demands;
   immoderate grief; immoderate laughter.
   [1913 Webster]

         So every scope by the immoderate use
         Turns to restraint.                      --Shak.

   Syn: Excessive; exorbitant; unreasonable; extravagant;
        intemperate; inordinate.
        [1913 Webster]

WordNet (r) 3.0 (2006):

immoderate
    adj 1: beyond reasonable limits; "immoderate laughter";
           "immoderate spending" [ant: moderate]

Moby Thesaurus II by Grady Ward, 1.0:

121 Moby Thesaurus words for "immoderate":
   a bit much, abandoned, acute, bibulous, boundless, crapulent,
   crapulous, cutthroat, cutting, dizzy, drastic, egregious, enormous,
   exacting, exaggerated, excessive, exorbitant, extortionate,
   extravagant, extreme, fabulous, fancy, fierce, furious, gigantic,
   gluttonous, go-go, gouging, great, grossly overpriced, high,
   hyperbolic, hypertrophied, incontinent, indulgent, inflationary,
   inordinate, intemperate, intense, irrepressible, keen, lax,
   licentious, loose, monstrous, nonrestrictive, out of bounds,
   out of control, out of hand, out of sight, outrageous, overbig,
   overdeveloped, overgreat, overgrown, overindulgent, overindulging,
   overlarge, overmuch, overpriced, overweening, permissive, piercing,
   preposterous, prodigal, prohibitive, rampant, reinless, rigorous,
   riotous, rough, self-indulgent, severe, sharp, skyrocketing,
   spiraling, splitting, steep, stiff, swinish, too much, tough,
   towering, unbridled, unchecked, uncoerced, uncompelled,
   unconscionable, unconstrained, uncontrolled, uncurbed,
   undisciplined, undue, unforced, unfrugal, ungoverned, uninhibited,
   unlimited, unmastered, unmeasurable, unmeasured, unmuzzled,
   unreasonable, unreined, unrepressed, unreserved, unrestrained,
   unrestrictive, unruly, unsubdued, unsuppressed, untempered,
   unthrifty, unwarranted, usurious, vehement, venomous, violent,
   virulent, wanton, wild