ENDODERM
endoderm, entoderm, endoblast, entoblast, hypoblast
(noun) the inner germ layer that develops into the lining of the digestive and respiratory systems
Source: WordNet® 3.1
Etymology
Noun
endoderm (plural endoderms)
One of the three tissue layers in the embryo of a metazoan animal. Through development, it will produce the digestive system of the adult.
Source: Wiktionary
En"do*derm, n. Etym: [Endo- + Gr. (Biol.)
(a) The inner layer of the skin or integument of an animal.
(b) The innermost layer of the blastoderm and the structures derived
from it; the hypoblast; the entoblast. See Illust. of Ectoderm.
Source: Webster’s Unabridged Dictionary 1913 Edition