Watermelon is the giant, sprawling-vine fruit of Citrullus lanatus, a member of the gourd family grown across the warm world for its crisp, intensely sweet, water-laden flesh. About 92% water, faintly fragrant and barely acidic, it is the archetypal summer fruit — eaten in dripping wedges, blended into agua fresca, salted, or cut into a melon-and-feta salad — and is botanically a berry, the giant fleshy pepo of a cucumber relative.