Noun | 1. | Hydrodamalis gigas - extinct large sirenian mammal formerly found near the Asiatic coast of the Bering Sea sea cow, sirenian, sirenian mammal - any of two families of large herbivorous aquatic mammals with paddle-shaped tails and flipper-like forelimbs and no hind limbs genus Hydrodamalis, Hydrodamalis - a genus of the family Dugongidae comprising only Steller's sea cow |