The Collaborative International Dictionary of English v.0.48:

Histrionic \His`tri*on"ic\, Histrionical \His`tri*on"ic*al\, a.
   [L. histrionicus: cf. F. histrionique. See Histrion.]
   1. Of or relating to the stage or a stageplayer; befitting a
      theatre; theatrical.
      [1913 Webster]

   2. Affectedly dramatic; insincerely emotional; -- sometimes
      used in a bad sense. -- His`tri*on"ic*al*ly, adv.
      [1913 Webster]

            Tainted with false and histrionic feeling. --De
                                                  Quincey.
      [1913 Webster]