What is the X in X-mas?
Spanish for "beer," from Latin cervisia "beer" (cf. Latin cerea "a Spanish beer"), from a Celtic *kerb- (cf. Gaulish curmi, Old Irish cuirm, Middle Irish coirm, Welsh cwrwf, Old Cornish coref "beer"), from Proto-Celtic *kormi-, perhaps from PIE root *krem-, also source of Latin cremare "to burn" (see cremation). "Connection with ceres (as a drink from grain) is very dubious" [Tucker].