What is the X in X-mas?
Old English hæð "untilled land, tract of wasteland," earlier "heather," influenced by Old Norse heiðr "field," from Proto-Germanic *haithiz (cf. Old Saxon hetha, Old High German heida "heather," Dutch heide "heath," Gothic haiþi "field"), from PIE *kaito "forest, uncultivated land" (cf. Old Irish ciad, Welsh coed, Breton coet "wood, forest").
Heb. 'arar, (Jer. 17:6; 48:6), a species of juniper called by the Arabs by the same name ('arar), the Juniperus sabina or savin. "Its gloomy, stunted appearance, with its scale-like leaves pressed close to its gnarled stem, and cropped close by the wild goats, as it clings to the rocks about Petra, gives great force to the contrast suggested by the prophet, between him that trusteth in man, naked and destitute, and the man that trusteth in the Lord, flourishing as a tree planted by the waters" (Tristram, Natural History of the Bible).