What is the X in X-mas?
mid-13c. (late 12c. as a surname), Anglo-French ivorie, from Old North French ivurie (12c.), from Latin eboreus "of ivory," from ebur (genitive eboris) "ivory," probably via Phoenician from an African source (cf. Egyptian ab "elephant," Coptic ebu "ivory"). Replaced Old English elpendban, literally "elephant bone." Applied in slang to articles made from it, such as dice (1830) and piano keys (1854). As a color, especially in reference to human skin, it is attested from 1580s. Ivories as slang for "teeth" dates from 1782. Related: Ivoried.
(Heb. pl. shenhabbim, the "tusks of elephants") was early used in decorations by the Egyptians, and a great trade in it was carried on by the Assyrians (Ezek. 27:6; Rev. 18:12). It was used by the Phoenicians to ornament the box-wood rowing-benches of their galleys, and Hiram's skilled workmen made Solomon's throne of ivory (1 Kings 10:18). It was brought by the caravans of Dedan (Isa. 21:13), and from the East Indies by the navy of Tarshish (1 Kings 10:22). Many specimens of ancient Egyptian and Assyrian ivory-work have been preserved. The word _habbim_ is derived from the Sanscrit _ibhas_, meaning "elephant," preceded by the Hebrew article (ha); and hence it is argued that Ophir, from which it and the other articles mentioned in 1 Kings 10:22 were brought, was in India.