Breadcrumb Home > Thesaurus > A Synonyms of amnion Find synonyms for: Noun 1. amnion, amniotic sac, amnios, sac usage: thin innermost membranous sac enclosing the developing embryo of higher vertebrates (reptiles, birds and mammals) WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.Definition and meaning of amnion (Dictionary) TrendingHere are the facts and trivia that people are buzzing about. Hanukkah Origins of the Christmas Holiday Jewish Holidays, 2010-2030 (A.M. 5770-5791) Western Christian Holidays, 2010-2030 Krampus: The Christmas Devil Kwanzaa ✖ Related Content Daily Word Quiz: praedial Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language