- The fruit of the watermelon plant, having a green rind and watery flesh that is bright red when ripe and contains black pips.
- A plant of the species Citrullus lanatus, bearing a melon-like fruit.
- A pinkish-red colour, like that of watermelon flesh.
"watermelon colour: "
- (pejorative, slang) An environmentalist with socialist leanings (from the similarity to the fruit, being green on the outside, and red on the inside).