Source : Webster's Revised Unabridged Dictionary (1913)

Animosity \An`i*mos"i*ty\, n.; pl. {Animosities}. [F.
   animosit['e], fr. L. animositas. See {Animose}, {Animate}, v.
   t.]
   1. Mere spiritedness or courage. [Obs.] --Skelton.

            Such as give some proof of animosity, audacity, and
            execution, those she [the crocodile] loveth.
                                                  --Holland.

   2. Violent hatred leading to active opposition; active
      enmity; energetic dislike. --Macaulay.

   Syn: Enmity; hatred; opposition. -- {Animosity}, {Enmity}.
        Enmity be dormant or concealed; animosity is active
        enmity, inflamed by collision and mutual injury between
        opposing parties. The animosities which were continually
        springing up among the clans in Scotland kept that
        kingdom in a state of turmoil and bloodshed for
        successive ages. The animosities which have been
        engendered among Christian sects have always been the
        reproach of the church.

              Such [writings] as naturally conduce to inflame
              hatreds and make enmities irreconcilable.
                                                  --Spectator.

              [These] factions . . . never suspended their
              animosities till they ruined that unhappy
              government.                         --Hume.

Source : WordNet®

animosity
     n : a feeling of ill will arousing active hostility [syn: {animus},
          {bad blood}]