citrus: [19] Latin citrus signified the ‘citron’, a tree (Citrus medica) of Asian origin with a lemon-like fruit which was the earliest of the citrus fruits to become known in the West. Like the fruit itself, the name is presumably of Eastern origin – perhaps from a non-Indo- European language from around the eastern end of the Himalayas. Citron is a French derivative of citrus, coined on the model of French limon ‘lemon’; it was borrowed into English in the 16th century. [citrus etymology, citrus origin, 英语词源]