watermelon Syllabification: (wa·ter·mel·on)Pronunciation: /ˈwôtərˌmelən, ˈwä-/Translate watermelon | into French | into German | into Italian | into Spanish Definition of watermelon noun 1the large melonlike fruit of a plant of the gourd family, with smooth green skin, red pulp, and watery juice. 2the widely cultivated African plant that yields the watermelon. Citrullus lanatus, family Cucurbitaceae watermelon in other Oxford dictionaries Definition of watermelon in the British & World English dictionary