What is the X in X-mas?
mid-13c., "noble, kind, gracious" (mid-12c. as a surname); late 14c., "of noble rank or birth, belonging to the gentry," from Late Latin gentilis "foreign, heathen, pagan," from Latin gentilis "person belonging to the same family, fellow countryman," from gentilis (adj.) "of the same family or clan," from gens (genitive gentis) "race, clan" (see gentle).
late 14c., "chivalrous person; member of the nobility;" see gentile (adj.). Also used during 14c. to mean both "one who is not a Christian" and "one who is not a Jew." The Latin word was used in Vulgate to translate Greek ethnikos, from ta ethne "the nations," which translated Hebrew ha goyim "the (non-Jewish) nations."
Note: Both the Old Testament and the New Testament tell of numerous conflicts between Jews and Gentiles. Figuratively, a “gentile” is any nonbeliever.
(Heb., usually in plural, goyim), meaning in general all nations except the Jews. In course of time, as the Jews began more and more to pride themselves on their peculiar privileges, it acquired unpleasant associations, and was used as a term of contempt. In the New Testament the Greek word Hellenes, meaning literally Greek (as in Acts 16:1, 3; 18:17; Rom. 1:14), generally denotes any non-Jewish nation.