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. Jewish Holidays, 2010-2030 (A.M. 5770-5791) Western Christian Holidays, 2010-2030 12 Steps to a New Year New Year's Resolution to Slim Down? Martin Luther King Speeches Books of the Bible: Old Testament Books in Order ✖ Related Content Daily Word Quiz: limpid Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language