Wa"ter*mel`on (?), n. (Bot.) The very large ovoid or roundish fruit of a cucurbitaceous plant (Citrullus vulgaris) of many varieties; also, the plant itself. The fruit sometimes weighs many pounds; its pulp is usually pink in color, and full of a sweet watery juice. It is a native of tropical Africa, but is now cultivated in many countries. See Illust. of Melon.

Wa"ter*mel`on (?), n. (Bot.) The very large ovoid or roundish fruit of a cucurbitaceous plant (Citrullus vulgaris) of many varieties; also, the plant itself. The fruit sometimes weighs many pounds; its pulp is usually pink in color, and full of a sweet watery juice. It is a native of tropical Africa, but is now cultivated in many countries. See Illust. of Melon.

• A plant of the genus Citrullus, a variety of melon.
  
• The fruit of the watermelon plant, having a green rind and watery flesh that is bright red when ripe and contains black pips.
  
• (derogatory slang) An environmentalist with socialist leanings (from the similarily to the fruit, being green on the outside, and red on the inside).