Al-lăn′tois or Ăl′lan-tois or Al-lăn′toid or Ăl′lan-toid, n.

n. [Gr. ἀλλαντοειδής, shaped like an ἀλλᾶς, Galen., ἀλλᾶς, gen. ἀλλάντος, forced-meat, sausage, gut, and εἶδος, shape.] (Anat.) A thin membrane, situated between the chorion and amnion, and forming one of the membranes which invest the fetus. Carpenter.