submersible Syllabification: (sub·mers·i·ble)Pronunciation: /səbˈmərsəbəl/Definition of submersible adjective designed to be completely submerged or to operate while submerged. noun a submersible boat or other craft, especially one designed for research and exploration. The ending of submersible is spelled -ible.submersible in other Oxford dictionaries Definition of submersible in the British & World English dictionary