The Collaborative International Dictionary of English v.0.48:

Vehemence \Ve"he*mence\, n. [L. vehementia: cf. F.
   v['e]h['e]mence.]
   [1913 Webster]
   1. The quality or state of being vehement; impetuous force;
      impetuosity; violence; fury; as, the vehemence of the
      wind; to speak with vehemence.
      [1913 Webster]

   2. Violent ardor; great heat; animated fervor; as, the
      vehemence of love, anger, or other passions.
      [1913 Webster]

            I . . . tremble at his vehemence of temper.
                                                  --Addison.
      [1913 Webster]

WordNet (r) 3.0 (2006):

vehemence
    n 1: intensity or forcefulness of expression; "the vehemence of
         his denial"; "his emphasis on civil rights" [syn:
         vehemence, emphasis]
    2: the property of being wild or turbulent; "the storm's
       violence" [syn: ferocity, fierceness, furiousness,
       fury, vehemence, violence, wildness]