The Collaborative International Dictionary of English v.0.48:

dogmatic \dog*mat"ic\ (d[o^]g*m[a^]t"[i^]k), dogmatical
\dog*mat`ic*al\ (d[o^]g*m[a^]t"[i^]*kal), a. [L. dogmaticus, Gr.
   dogmatiko`s, fr. do`gma: cf. F. dogmatique.]
   1. Pertaining to a dogma, or to an established and authorized
      doctrine or tenet.
      [1913 Webster]

   2. Asserting a thing positively and authoritatively;
      positive; magisterial; hence, arrogantly authoritative;
      overbearing.
      [1913 Webster]

            Critics write in a positive, dogmatic way. --
                                                  Spectator.
      [1913 Webster]

            [They] are as assertive and dogmatical as if they
            were omniscient.                      -- Glanvill.
      [1913 Webster]

   Dogmatic theology. Same as Dogmatics.

   Syn: Magisterial; arrogant. See Magisterial.
        [1913 Webster]

WordNet (r) 3.0 (2006):

dogmatical
    adj 1: characterized by assertion of unproved or unprovable
           principles [syn: dogmatic, dogmatical]