| Noun | 1. | omentum - a fold of peritoneum supporting the visceraperitoneum - a transparent membrane that lines the abdominal cavity in mammals and covers most of the viscera caul, gastrocolic omentum, greater omentum - part of the peritoneum attached to the stomach and to the colon and covering the intestines lesser omentum - a part of the peritoneum attached to the stomach and liver and supporting the hepatic vessels |