What is the X in X-mas?
Old English hal "entire, unhurt, healthy," from Proto-Germanic *khailaz "undamaged" (cf. Old Saxon hel, Old Norse heill, Old Frisian hal, Middle Dutch hiel, Dutch heel, Old High German, German heil "salvation, welfare"), from PIE *koilas (cf. Old Church Slavonic celu "whole, complete;" see health). The spelling with wh- developed early 15c. The sense in whole number is from early 14c. For phrase whole hog, see hog.
"entire body or company; the full amount," late 14c., from whole (adj.).
Not wounded, injured, or impaired; sound or unhurt.
Having been restored; healed.