| 1. | any sirenian, as the manatee or dugong. |
| 2. | Obsolete. the hippopotamus. |
| sea cow n. Any of several large, cylindrical, herbivorous marine mammals of the order Sirenia, having a paddlelike tail and rounded front flippers, including the manatee, dugong, and the very large species Hydrodamalis stelleri of the northern Pacific that became extinct in the late 1700s. Also called sirenian. |