boatbill Syllabification: (boat·bill)Pronunciation: /ˈbōtˌbil/Definition of boatbill noun (also boat-billed heron) a small Central and South American heron with a broad, flattened bill and a prominent black crest. Cochlearius cochlearius, family Ardeidae boatbill in other Oxford dictionaries Definition of boatbill in the British & World English dictionary