ectoderm
ec.to.derm or ec.to.der.mic \'ek-t*-.d*rm\ \.ek-t*-'d*r-m*l\ \-mik\ n [ISV ect- + Gk derma skin - more at DERM-] 1: the outer cellular membrane of a diploblastic animal 2a: the outermost of the three primary germ layers of an embryo 2b: a tissue (as neural tissue) derived from this germ layer - ec.to.der.mal aj