费氏榄仁（学名：Terminalia ferdinandiana），又名卡卡杜李（Kakadu plum）、公山羊李（Billygoat plum），是使君子科诃子属的一种木本植物。原产于澳洲，广泛的分布在澳洲西北部至北领地安恒地区（Arnhem Land）东部的热带森林里。

费氏榄仁的果实是目前已知维生素C含量最高的水果，每100公克的果肉含有3200～5000毫克的维生素C，其维生素C的含量比柳橙高出100倍。柳橙每100公克的果肉只含有50毫克的维生素C。

Terminalia ferdinandiana, also called the gubinge, billygoat plum, Kakadu plum or murunga, is a flowering plant in the family Combretaceae, native to Australia, widespread throughout the tropical woodlands from northwestern Australia to eastern Arnhem Land. It has a high concentration of vitamin C in its fruit: recorded concentrations of 2300–3150 mg/100 g wet weight and occasionally as high as 5300 mg/100 g, compared with 50 mg/100 g for oranges, ranks among the highest known of any natural source.