chorionic villus sampling Syllabification: (cho·ri·on·ic vil·lus sam·pling) (abbreviation: CVS)Definition of chorionic villus sampling noun Medicine a test made in early pregnancy to detect congenital abnormalities in the fetus. A tiny tissue sample is taken from the villi of the chorion, which forms the fetal part of the placenta. chorionic villus sampling in other Oxford dictionaries Definition of chorionic villus sampling in the British & World English dictionary