choriocarcinoma Syllabification: (cho·ri·o·car·ci·no·ma)Pronunciation: /ˌkôrēōˌkärsəˈnōmə/Definition of choriocarcinoma noun (plural choriocarcinomas or choriocarcinomata /-ˈnōmətə/) Medicine a malignant tumor of the uterus that originates in the cells of the chorion of a fetus. choriocarcinoma in other Oxford dictionaries Definition of choriocarcinoma in the British & World English dictionary