Rahere, regardless of the varied definitions of the word today by English speaking nations, the etymology of the word is from Old English, hāligdæg (hālig "holy" + dæg "day.) A quick google search will confirm this from a number of different sources.

When I first came to Mudcat I got confused by the UK usage of the word to mean what we in the USA refer to as a vacation. It didn't take long to figure out from the context of posts, and now, when I see some one refer to going on holiday I understand it is probably a post from some one across the pond who is taking some recreational time off work. Etymology of 'vacation' is from Latin, to Old French to Middle English.

Interesting to know on both counts for those of us who enjoy a little trivia, but as long as we can figure out one another's meaning, that is all that matters. AT least to me.