Dear Ben1011, I love etymologies, so I did some poking around for HOORAY...and quite interesting too!
The experts seem uncertain, but they speculate hurrah and hooray may derive from the Old German saliors' cry of "huzza." I found one reference to HUZZA as early as 1573, although other sources say 1686 is the earliest usage located so far. (Also, others claim the word came from invading Mongols...)
Anyway, the sailors apparently used huzza (heisau! hissa!) as a kind of onomatopoeic hauling or hoisting cry, and then it got extended to a cheer or salute whenever friends or someone they admired came on board...then you found the word in Sweden and Denmark, along with spreading through the military.
* * * Okay, that should get you started, and welcome to AnswerMug. (Oh wait! You joined April 1, 2016, I thought it was yesterday! Well happy one-year anniversary here then.)
This post was edited by Benedict Arnold at April 3, 2017 9:16 PM MDT
I have a Page A Day calendar titled "Forgotten English" which has an archaic word and it origin every day. Some are pretty cool and I might use them. Others are too obscure and seem to be just forgotten short lived slang.
Sorry, this is not the answer to your question but it's still interesting. We were in France during the olympics last summer. During a basketball game when ever the French team would score, the announcers would yell, "Weeee!" At first we thought those announcers were really having a great time. Then we realized they were saying, "YES!" in French. Maybe the word "yay" grew out of some modification of YES! or YEAH!
This post was edited by CallMeIshmael at April 3, 2017 10:15 PM MDT
Benedict Arnold 