The Collaborative International Dictionary of English v.0.48:

Exclamation \Ex`cla*ma"tion\, n. [L. exclamatio: cf. F.
   exclamation.]
   1. A loud calling or crying out; outcry; loud or emphatic
      utterance; vehement vociferation; clamor; that which is
      cried out, as an expression of feeling; sudden expression
      of sound or words indicative of emotion, as in surprise,
      pain, grief, joy, anger, etc.
      [1913 Webster]

            Exclamations against abuses in the church. --Hooker.
      [1913 Webster]

            Thus will I drown your exclamations.  --Shak.
      [1913 Webster]

            A festive exclamation not unsuited to the occasion.
                                                  --Trench.
      [1913 Webster]

   2. (Rhet.) A word expressing outcry; an interjection; a word
      expressing passion, as wonder, fear, or grief.
      [1913 Webster]

   3. (Print.) A mark or sign by which outcry or emphatic
      utterance is marked; thus [!]; -- called also exclamation
      point.
      [1913 Webster]

WordNet (r) 3.0 (2006):

exclamation
    n 1: an abrupt excited utterance; "she gave an exclamation of
         delight"; "there was much exclaiming over it" [syn:
         exclamation, exclaiming]
    2: a loud complaint or protest or reproach
    3: an exclamatory rhetorical device; "O tempore! O mores" [syn:
       ecphonesis, exclamation]