What is the X in X-mas?
late 13c. "unsalted, pure, sweet, eager," metathesis of Old English fersc "unsalted," from West Germanic *friskaz (cf. Old Frisian fersk, Middle Dutch versch, Dutch vers, Old High German frisc, German frisch "fresh").
Probably cognate with Old Church Slavonic presinu "fresh," Lithuanian preskas "sweet." The metathesis, and the expanded Middle English senses of "new, pure, eager" are probably by influence of (or in some instances, from) Old French fres (fem. fresche), from Proto-Germanic *frisko-, and thus related to the English word. The Germanic root also is the source of Italian and Spanish fresco. Related: Freshly; freshness.
"impudent, presumptuous," 1848, U.S. slang, probably from German frech "insolent, cheeky," from Old High German freh "covetous," related to Old English frec "greedy, bold" (see freak (n.)).
[first two senses perhaps related to German frech, ''impudent''; third sense said to have originated with a 1970s rock group called the Fantastic Romantic Five MCs, who said ''We're fresh out of the pack, you gotta stand back, we got one Puerto Rican and the rest are black'']