What is the X in X-mas?
early 13c., from Anglo-French bascat, origin obscure despite much speculation. On one theory from Latin bascauda "kettle, table-vessel," said by the Roman poet Martial to be from Celtic British and perhaps cognate with Latin fascis "bundle, faggot," in which case it probably originally meant "wicker basket." But OED frowns on this, and there is no evidence of such a word in Celtic unless later words in Irish and Welsh, counted as borrowings from English, are original.
There are five different Hebrew words so rendered in the Authorized Version: (1.) A basket (Heb. sal, a twig or osier) for holding bread (Gen. 40:16; Ex. 29:3, 23; Lev. 8:2, 26, 31; Num. 6:15, 17, 19). Sometimes baskets were made of twigs peeled; their manufacture was a recognized trade among the Hebrews. (2.) That used (Heb. salsilloth') in gathering grapes (Jer. 6:9). (3.) That in which the first fruits of the harvest were presented, Heb. tene, (Deut. 26:2, 4). It was also used for household purposes. In form it tapered downwards like that called _corbis_ by the Romans. (4.) A basket (Heb. kelub) having a lid, resembling a bird-cage. It was made of leaves or rushes. The name is also applied to fruit-baskets (Amos 8:1, 2). (5.) A basket (Heb. dud) for carrying figs (Jer. 24:2), also clay to the brick-yard (R.V., Ps. 81:6), and bulky articles (2 Kings 10:7). This word is also rendered in the Authorized Version "kettle" (1 Sam. 2:14), "caldron" (2 Chr. 35:13), "seething-pot" (Job 41:20). In the New Testament mention is made of the basket (Gr. kophinos, small "wicker-basket") for the "fragments" in the miracle recorded Mark 6:43, and in that recorded Matt. 15:37 (Gr. spuris, large "rope-basket"); also of the basket in which Paul escaped (Acts 9:25, Gr. spuris; 2 Cor. 11: 33, Gr. sargane, "basket of plaited cords").