An invasive malignant neoplasm that arises from the ovary and is characterized by the presence of malignant epithelial cells that contain intracytoplasmic mucin and may resemble the epithelial cells of the endocervix or gastrointestinal tract. It includes mucinous adenocarcinoma and mucinous adenocarcinofibroma. The disease is mucinous ovarian cancer (MONDO_0024282, a Monarch Disease Ontology entry). Also known as: malignant ovarian mucinous neoplasm, malignant ovarian mucinous tumor, malignant ovarian mucinous tumour, ovarian mucinous neoplasm, malignant.