What is the X in X-mas?
equivalent of Old English broþerrede "fellowship, brotherhood," with ending as in kindred; in early Middle English the word was brotherhede with ending as in maidenhead. The modern word, with -hood, is from 15c. Originally "relationship of a brother," also "friendly companionship." Concrete sense of "an association, a fraternity" is from mid-14c. in the Middle English word (later also "labor union," 1880s). Old English also had broðorscipe "brothership," broðorsibb "kinship of brothers."
Oh, the Protestants hate the Catholics,
And the Catholics hate the Protestants,
And the Hindus hate the Muslims,
And everybody hates the Jews.
[Tom Lehrer, "National Brotherhood Week" lyrics, 1965]