ectoderm

from WordNet (r) 3.0 (2006)

ectoderm
    n 1: the outer germ layer that develops into skin and nervous
         tissue [syn: {ectoderm}, {exoderm}, {ectoblast}]

from The Collaborative International Dictionary of English v.0.48

Ectoderm \Ec"to*derm\, n. [Ecto- + -derm.] (Biol.)
   (a) The outer layer of the blastoderm; epiblast.
   (b) The external skin or outer layer of an animal or plant,
       this being formed in an animal from the epiblast. See
       Illust. of {Blastoderm}. Ectodermal