What is the X in X-mas?
c.1300, "miracle," also "wonderful story or legend," from Old French merveille "a wonder, surprise, miracle," from Vulgar Latin *miribilia (also source of Spanish maravilla, Portuguese maravilha, Italian maraviglia), altered from Latin mirabilia "wonderful things," from neuter plural of mirabilis "wonderful, marvelous, extraordinary; strange, singular," from mirari "to wonder at," from mirus "wonderful" (see smile). A neuter plural treated in Vulgar Latin as a feminine singular. Related: Marvels.
c.1300, "to be filled with wonder," from Old French merveillier "to wonder at, be astonished," from merveille (see marvel (n.)). Related: Marveled; marveling.