The Collaborative International Dictionary of English v.0.48:

Myoepithelial \My`o*ep`i*the"li*al\, a. [Myo- + epithelial.]
   1. (Biol.) Derived from epithelial cells and destined to
      become a part of the muscular system; -- applied to
      structural elements in certain embryonic forms.
      [1913 Webster]

   2. (Zool.) Having the characteristics of both muscle and
      epithelium; as, the myoepithelial cells of the hydra.
      [1913 Webster]