The Collaborative International Dictionary of English v.0.48:

Intolerable \In*tol"er*a*ble\, a. [F. intol['e]rable, L.
   intolerabilis. See In- not, and Tolerable.]
   [1913 Webster]
   1. Not tolerable; not capable of being borne or endured; not
      proper or right to be allowed; insufferable;
      insupportable; unbearable; as, intolerable pain;
      intolerable heat or cold; an intolerable burden.
      [1913 Webster]

            His insolence is more intolerable
            Than all the princes in the land beside. --Shak.
      [1913 Webster]

   4. Enormous.
      [1913 Webster]

            This intolerable deal of sack.        --Shak.
      -- In*tol"er*a*ble*ness, n. -- In*tol"er*a*bly, adv.
      [1913 Webster]

WordNet (r) 3.0 (2006):

intolerable
    adj 1: incapable of being put up with; "an intolerable degree of
           sentimentality" [syn: intolerable, unbearable,
           unendurable] [ant: tolerable]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "intolerable":
   a bit much, abhorrent, absolute, arrant, classical, complete,
   consummate, crass, decided, definitive, dislikable, displeasing,
   distasteful, downright, egregious, exceptionable, flagrant,
   glaring, gross, impossible, inadmissible, indefensible,
   insufferable, insupportable, mislikable, objectionable, odious,
   out-and-out, outright, past bearing, perfect, positive, precious,
   profound, pronounced, proper, rank, regular, shattering, shocking,
   stark, stark-staring, superlative, surpassing, the veriest,
   thorough, thoroughgoing, too much, total, unacceptable, unbearable,
   uncongenial, unconscionable, undeniable, undesirable, unendurable,
   unequivocal, uninviting, unlikable, unlovable, unmitigated,
   unpleasant, unqualified, unrelieved, unspoiled, unsuitable,
   unsupportable, untenable, utter