Entry 1 sense Webster, 1913 manatee /mănʹə-tēˊ/ · man·a·tee · IPA /ˈmæn.əˌtiː/ 01 n. Any species of Trichechus, a genus of sirenians; -- called also sea cow. 1. Any species of Trichechus, a genus of sirenians; -- called also sea cow.(Zool.) Also: sea cow