What is the X in X-mas?
Old English wid, from Proto-Germanic *widas (cf. Old Saxon, Old Frisian wid, Old Norse viðr, Dutch wijd, Old High German wit, German weit), perhaps from PIE *wi-ito-, from root *wi- "apart, away." Wide open "unguarded, exposed to attack" (1915) originally was in boxing, etc. Wide awake (adj.) is first recorded 1818; figurative sense of "alert, knowing" is attested from 1833.