The Underhusen and Overhusen are the Upper and Lower houses of our Legislature, the Sorting. However interestingly enough the original terms were slightly different, the original terms were Underhuset and Overhuset. In fact Underhusen and Overhusen may not be 'true' words, and instead created here in Wintreath. In fact the meaning of the terms Overhuset was, "Upper House" and the meaning of the Term Underhuset transliterates roughly to, "Lower House" or "House of the Commons."
You see the first use of the Word Underhuset and Overhusen is on
October 22, 2013 and is post #272 which was made by Charax. However interestingly enough the earliest use of Overhusen on the Forum is on
October 30, 2013 and is post #674 made by Charax. Note that in the same topic the Underhusen and Overhusen are still referred to as Underhuset and Overhuset. Meaning that Between October 26, 2013 and October 30th, 2013 the word Overhusen was created.
The origins of the term Underhusen are harder to track down, due to the fact that the earliest usage of Underhusen I was able to find(using the built in search function), was on
November 24, 2013 post #1848 made by Dawsinian during the first Underhusen campaign. However due to the fact that this was a long time after the first use of Overhusen, I can somewhat safely say that the word Underhusen was not used on the forum prior to that, but probably existed.
Therefor the creation and adoption of the term Overhusen was between October 26, 2013 and October 30th, 2013 and it was probably around that time that Underhuset became Underhusen.
Also keep in mind that these are all from the search feature on this forum, and that this only counts areas I have access too.