narrowboat Syllabification: (nar·row·boat)Pronunciation: /ˈnarōˌbōt/Definition of narrowboat noun British a canal boat less than 7 feet (2.1 m) wide with a maximum length of 70 feet (21.3 m) and steered with a tiller rather than a wheel. narrowboat in other Oxford dictionaries Definition of narrowboat in the British & World English dictionary