What is the X in X-mas?
Old English wundor "marvelous thing, marvel, the object of astonishment," from Proto-Germanic *wundran (cf. Old Saxon wundar, Middle Dutch, Dutch wonder, Old High German wuntar, German wunder, Old Norse undr), of unknown origin. In Middle English it also came to mean the emotion associated with such a sight (late 13c.). The verb is from Old English wundrian. Used colloquially in Pennsylvania German areas in some transitive senses (It wonders me that ... for "I wonder why ..."); this was common in Middle English and as late as Tindale (1533), and a correspondent reports the usage also yet survives in Yorkshire/Lincolnshire. Related: Wondered, wondering, wonders.