bitter melon

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A tropical annual vine (Momordica charantia) native to Asia, having yellow flowers and orange, warty fruits that open at maturity to expose red-coated seeds. Various parts of the plant are used in traditional medicine or for food.
• noun The immature green fruit of this plant, eaten as a vegetable.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a plant, Momordica charantia, which produces a bitter, though edible, fruit
• noun the fruit of the bitter melon