The Collaborative International Dictionary of English v.0.48:

Acrimony \Ac"ri*mo*ny\, n.; pl. Acrimonies. [L. acrimonia, fr.
   acer, sharp: cf. F. acrimonie.]
   1. A quality of bodies which corrodes or destroys others;
      also, a harsh or biting sharpness; as, the acrimony of the
      juices of certain plants. [Archaic] --Bacon.
      [1913 Webster]

   2. Sharpness or severity, as of language or temper;
      irritating bitterness of disposition or manners.
      [1913 Webster]

            John the Baptist set himself with much acrimony and
            indignation to baffle this senseless arrogant
            conceit of theirs.                    --South.
      [1913 Webster]

   Syn: Acrimony, Asperity, Harshness, Tartness.

   Usage: These words express different degrees of angry feeling
          or language. Asperity and harshness arise from angry
          feelings, connected with a disregard for the feelings
          of others. Harshness usually denotes needless severity
          or an undue measure of severity. Acrimony is a biting
          sharpness produced by an imbittered spirit. Tartness
          denotes slight asperity and implies some degree of
          intellectual readiness. Tartness of reply; harshness
          of accusation; acrimony of invective.
          [1913 Webster]

                In his official letters he expressed, with great
                acrimony, his contempt for the king's character.
                                                  --Macaulay.
          [1913 Webster]

                It is no very cynical asperity not to confess
                obligations where no benefit has been received.
                                                  --Johnson.
          [1913 Webster]

                A just reverence of mankind prevents the growth
                of harshness and brutality.       --Shaftesbury.
          [1913 Webster] acrisia

WordNet (r) 3.0 (2006):

acrimony
    n 1: a rough and bitter manner [syn: bitterness, acrimony,
         acerbity, jaundice, tartness, thorniness]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "acrimony":
   acerbity, acid, acidity, acidness, acidulousness, acridity,
   animosity, animus, antipathy, asperity, astringency, bad blood,
   bile, bite, bitingness, bitter feeling, bitter resentment,
   bitterness, bitterness of spirit, causticity, causticness, choler,
   corrosiveness, edge, feud, fierceness, gall, gnashing of teeth,
   grip, hard feelings, harshness, heartburning, ill blood,
   ill feeling, ill will, incisiveness, keenness, malevolence, malice,
   malignity, mordacity, mordancy, piercingness, poignancy, point,
   rancor, rankling, rigor, roughness, severity, sharpness, slow burn,
   soreness, sourness, spite, spleen, stabbingness, sting, stridency,
   stringency, tartness, teeth, trenchancy, vehemence, vendetta,
   venom, violence, virulence, vitriol