- the outermost of the two membranes that completely envelop a fetus
- the outer membrane or shell of the eggs of insects and other invertebrates
Origin of chorionModern Latin from Classical Greek chorion, fetal membrane: for Indo-European base see yarn
The outer membrane enclosing the embryo in reptiles, birds, and mammals. In placental mammals it contributes to the development of the placenta.
Origin of chorionGreek khorion ; see gherə- in Indo-European roots.
From Late Latin chorion, from Ancient Greek χοριον (khorion, “membrane surrounding the fetus, afterbirth”).