A malignant germ cell tumor that arises from the stomach. It includes choriocarcinoma and immature teratoma. The disease is malignant gastric germ cell tumor (MONDO_0003112). Also known as: germ cell tumor of the stomach, germ cell tumour of the stomach, malignant gastric germ cell neoplasm, malignant germ cell neoplasm of stomach, malignant germ cell neoplasm of the stomach, malignant germ cell tumor of stomach, malignant germ cell tumor of the stomach, malignant germ cell tumour of stomach.