Pronunciation: (am'nē-un), [key]
—pl. -ni•ons, -ni•aPronunciation: (-nē-u). [key]
1. Anat., Zool.the innermost of the embryonic or fetal membranes of reptiles, birds, and mammals; the sac in which the embryo is suspended.
2. Zool.a similar membrane of insects and other invertebrates.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.