What is the X in X-mas?
Hebrew ephod, from aphad "to put on."
something girt, a sacred vestment worn originally by the high priest (Ex. 28:4), afterwards by the ordinary priest (1 Sam. 22:18), and characteristic of his office (1 Sam. 2:18, 28; 14:3). It was worn by Samuel, and also by David (2 Sam. 6:14). It was made of fine linen, and consisted of two pieces, which hung from the neck, and covered both the back and front, above the tunic and outer garment (Ex. 28:31). That of the high priest was embroidered with divers colours. The two pieces were joined together over the shoulders (hence in Latin called superhumerale) by clasps or buckles of gold or precious stones, and fastened round the waist by a "curious girdle of gold, blue, purple, and fine twined linen" (28:6-12). The breastplate, with the Urim and Thummim, was attached to the ephod.
part of the ceremonial dress of the high priest of ancient Israel described in the Old Testament (Ex. 28:6-8; 39:2-5). It was worn outside the robe and probably kept in place by a girdle and by shoulder pieces, from which hung the breast piece (or pouch) containing the sacred lots (divinatory objects), Urim and Thummim, whose precise function is now unknown. It is uncertain whether the ephod covered the back, encircling the body like a kind of waistcoat, or only the front. It was not a garment in the ordinary sense, and its association with the sacred lots indicates that the ephod was used for divination.