Definition of Sirenia
: an order of large aquatic herbivorous mammals including the manatee, dugong, Steller's sea cow, and several fossil forms that have the tail horizontally flattened and expanded into a broad rounded or bilobed fin, the hind limbs rudimentary or wanting and the front ones paddle-shaped, and jaws with horny plates on the front part and usually numerous flat-crowned molar teeth
Love words? You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.
Start your free trial today and get unlimited access to America's largest dictionary, with:
- More than 250,000 words that aren't in our free dictionary
- Expanded definitions, etymologies, and usage notes
- Advanced search features
- Ad free!
Origin and Etymology of sirenia
New Latin, from Latin siren + New Latin -ia
Seen and Heard
What made you want to look up Sirenia? Please tell us where you read or heard it (including the quote, if possible).