manatee Syllabification: (man·a·tee)Pronunciation: /ˈmanəˌtē/Definition of manatee noun an aquatic mammal with a rounded tail flipper, living in shallow coastal waters and adjacent rivers of the tropical Atlantic. Family Trichechidae and genus Trichechus: three species, all of which are endangered, including the West Indian manatee (T. manatus) Origin: mid 16th century: from Spanish manati, from Carib manátimanatee in other Oxford dictionaries Definition of manatee in the British & World English dictionary