chorioallantois

American

[kawr-ee-oh-uh-lan-toh-is, ‑tois, kohr‑] / ˌkɔr i oʊ əˈlæn toʊ ɪs, ‑tɔɪs, ˌkoʊr‑ /

noun

Embryology, Zoology.

a vascular, extraembryonic membrane of birds, reptiles, and certain mammals, formed by the fusion of the wall of the chorion with the wall of the allantois.

First recorded in 1930–35

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023