"type of coniferous tree noted for its slow growth and hard timber," late Old English ceder, blended in Middle English with Old French cedre, both from Latin cedrus, from Greek kedros "cedar, juniper," a word of uncertain origin.
True cedars are those native to Lebanon and the Levant, western North Africa, and the Himalayas, but the name has been applied to many more or less similar trees in North America and the tropics. Cedar oil was used by the Egyptians in embalming as a preservative against decay and the word for it was used figuratively for "immortality" by the Romans. Cedar chest, one made of cedar wood to protect contents from moths and other insects, is attested from 1722. Related: Cedrine.
any tree of the genus Citrus, or its fruit, 1825, from the Modern Latin genus name, from Latin citrus "citron tree," the name of an African tree with aromatic wood and lemon-like fruit, the first citrus fruit to become available in the West. The name, like the tree, is probably of Asiatic origin [OED] or from a lost non-IE Mediterranean language [de Vaan]. But Klein and others trace it to Greek kedros "cedar," perhaps via Etruscan (a suggested by the change of -dr- to -tr-).