Source : Webster's Revised Unabridged Dictionary (1913)

Exacerbation \Ex*ac`er*ba"tion\n. [Cf. F. exacerbation.]
   1. The act rendering more violent or bitter; the state of
      being exacerbated or intensified in violence or malignity;
      as, exacerbation of passion.

   2. (Med.) A periodical increase of violence in a disease, as
      in remittent or continious fever; an increased energy of
      diseased and painful action.

Source : WordNet®

exacerbation
     n 1: action that makes a problem or a disease (or its symptoms)
          worse; "the aggravation of her condition resulted from
          lack of care" [syn: {aggravation}]
     2: violent and bitter exasperation; "his foolishness was
        followed by an exacerbation of their quarrel"