The Collaborative International Dictionary of English v.0.48:
Embryonic \Em`bry*on"ic\, a. (Biol.) Of or pertaining to an embryo; embryonal; rudimentary. [1913 Webster] Embryonic sac or Embryonic vesicle (Bot.), the vesicle within which the embryo is developed in the ovule; -- sometimes called also amnios sac, and embryonal sac. [1913 Webster]