Chorion

//ˈkɔɹiɑn// noun

noun ·Uncommon ·Advanced level

Definitions

Noun
  1. 1
    The protective and nutritive membrane in higher vertebrates that attaches the fetus to the uterus.

    "2002, Rovert E. A. Stewart, Barbara E. Stewart, Female Reproductive Systems, entry in Encyclopedia of Marine Mammals, page 425, The allantois fuses with the chorion, forming a small round area, the allentochorion. This region becomes the placenta (Fig. 3)."

  2. 2
    the outermost membranous sac enclosing the embryo in higher vertebrates (reptiles, birds and mammals) wordnet
  3. 3
    The outer case of an insect egg.

    "The chorion has a predominantly lamellar structure, the lamellae being two-dimensional networks of protein fibrils."

  4. 4
    The outer membrane of seeds of plants.

Example

More examples

"2002, Rovert E. A. Stewart, Barbara E. Stewart, Female Reproductive Systems, entry in Encyclopedia of Marine Mammals, page 425, The allantois fuses with the chorion, forming a small round area, the allentochorion. This region becomes the placenta (Fig. 3)."

Etymology

From Late Latin chorion, from Ancient Greek χόριον (khórion, “membrane surrounding the fetus, afterbirth”).

Related phrases

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.