What does chorionic mean?
"Chorionic" is a medical adjective meaning relating to the chorion, the outermost of the membranes that surround an embryo during development. In mammals, the chorion plays a crucial role: together with other tissues it helps form the placenta, the organ through which the fetus receives oxygen and nutrients from its mother. The word appears most often in clinical and scientific contexts, particularly obstetrics. Its most familiar uses are "chorionic villus sampling," a prenatal diagnostic procedure in which a small sample of placental tissue is tested for genetic conditions, and "human chorionic gonadotropin" (hCG), the hormone produced by chorionic tissue whose presence in urine is what home pregnancy tests detect. Because of these associations, "chorionic" carries a precise, clinical register — readers encountering it are usually dealing with pregnancy, prenatal screening, or developmental biology rather than everyday conversation. It derives ultimately from the Greek "chorion," meaning skin or membrane.
adjectiveRelating to the chorion, the outermost membrane surrounding an embryo or fetus that contributes to the formation of the placenta.
- Relating to or consisting of the chorion, the outer embryonic membrane of reptiles, birds, and mammals that in mammals contributes to the placenta.
"The obstetrician recommended chorionic villus sampling to test for chromosomal abnormalities."
"Levels of human chorionic gonadotropin rise sharply during early pregnancy."
"Chorionic villus sampling can be performed earlier in gestation than amniocentesis."
Every positive pregnancy test you've ever taken worked because of a chorionic hormone — hCG is literally produced by the chorion.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of chorionic
"Chorionic" derives from "chorion," the anatomical name for the outer embryonic membrane, which was borrowed into New Latin from ancient Greek "chórion," meaning a skin or leather covering, related to "chóra," a bodily region or space. The adjective form arose in nineteenth-century scientific writing as anatomy and embryology formalized their terminology around Greek roots. It shares this Greek origin with compound terms such as "chorioallantoic" and "hemochorial," both used to classify types of placentas across mammalian species.
Related word forms
How chorionic is actually used
Strictly a medical and scientific term, used almost exclusively in embryology, obstetrics, and clinical contexts; it would rarely appear outside technical writing except perhaps in discussions of prenatal testing or pregnancy hormones such as hCG (human chorionic gonadotropin).
Easily confused with chorionic
"Choral" relates to a choir or choral music, while "chorionic" relates to the chorion, the embryonic membrane.