Chorionic

Part of speech: adjective

Definitions

1. Relating to the outermost membrane surrounding an embryo in mammals
2. referring to tissues involved in the formation of the placenta
3. characterizing structures that play a crucial role in fetal development and nutrition

Etymology: Chorionic is a plain technical coinage: English "chorion" with the adjectival suffix "-ic" attached. The suffix reaches English through Latin "-icus", which passed into Old French as "-ique" and then into Middle English as "-ik" before settling into the modern "-ic" form. That suffix has been attached to countless Greek and Latin roots, so the ending here tells you little beyond "relating to." The base word is the interesting part. "Chorion" comes from Greek "khorion," the outermost membrane surrounding an embryo, and the term entered English as a medical noun for that fetal membrane. Modern anatomists use "chorionic" for the tissues that give rise to the placenta, so the word names a specific layer of embryonic tissue rather than the placenta as a whole.

Synonyms: placental, embryonic, fetal