col·o·cynth 
(kŏlə-sĭnth′)
(kŏlə-sĭnth′)n.
1. A tendril-bearing Old World vine (Citrullus colocynthis) bearing yellowish, green-mottled fruits the size of small lemons.
2. The fruit of this plant, whose dried, bitter, spongy pulp is a very strong laxative. In both senses also called bitter apple.
[Latin colocynthis, from Greek kolokunthis, from kolokunthē, round gourd.]