ECTODERM
ectoderm, exoderm, ectoblast
(noun) the outer germ layer that develops into skin and nervous tissue
Source: WordNet® 3.1
Etymology
Noun
ectoderm (plural ectoderms)
(biology) Outermost of the three tissue layers in the embryo of a metazoan animal. Through development, it will produce the epidermis (skin) and nervous system of the adult.
Source: Wiktionary
Ec"to*derm, n. Etym: [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.
Source: Webster’s Unabridged Dictionary 1913 Edition