sea cow vs sirenian

sea cow and sirenian both are nouns.

Word	Noun	Adjective	Verb	Adverb
sea cow	Yes	No	No	No
sirenian	Yes	No	No	No

As nouns, sea cow and sirenian are synonyms defined as:

sea cow and sirenian: any of two families of large herbivorous aquatic mammals with paddle-shaped tails and flipper-like forelimbs and no hind limbs

Other synonyms of sea cow include sirenian mammal.

sea cow (noun)	sirenian (noun)
any of two families of large herbivorous aquatic mammals with paddle-shaped tails and flipper-like forelimbs and no hind limbs	any of two families of large herbivorous aquatic mammals with paddle-shaped tails and flipper-like forelimbs and no hind limbs