The American Heritage® Dictionary of the English Language, 4th Edition
n. A herbivorous marine mammal (Dugong dugon), native to tropical coastal waters of the Indian Ocean, Red Sea, and southwest Pacific Ocean and having flipperlike forelimbs and a deeply notched tail fin.
n. A plant-eating aquatic marine mammal, of the genus Dugong, found in tropical regions. Dugong dugon.
the GNU version of the Collaborative International Dictionary of English
n. An aquatic herbivorous mammal (Halicore dugong), of the order Sirenia, allied to the manatee, but with a bilobed tail. It inhabits the Red Sea, Indian Ocean, East Indies, and Australia.
The Century Dictionary and Cyclopedia
n. A large aquatic herbivorous mammal of the order Sirenia, Halicore dugong, of the Indian seas.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. sirenian tusked mammal found from eastern Africa to Australia; the flat tail is bilobate
Word Usage
"I know that on the eastern coast of Africa is found a smaller species of walrus called the dugong: it has long incisor teeth, but not tusks; and certainly resembles a seal rather than a walrus.’"