Webster’s Revised Unabridged Dictionary · 1913
Hypoblast
Hy′po·blast (·blăst), n. [Pref. hypo- + -blast.] (Biol.) The inner or lower layer of the blastoderm; — called also endoderm, entoderm, and sometimes hypoderm. See Illust. of Blastoderm, Delamination, and Ectoderm.