An elitist trade, forum troll of WoW, who at times is quite vulgar, is given to each realm to piss those off, and make others quite happy. A Gaettusk's duty is to lead the other trolls.
Noob on Forum LFG: The Gaettusk is a total fag.
Gaettusk Follower: LOLOZLOZLZ U TOATAL FIEGIT K
Popularized by Japanese giant robot type shows, the term literally refers to the act of merging two seperate entities. It is often interchangable with similiar terms such as fusion, combination, joining, etc.
(i.e. Shinkon Gattai Godannar roughly translates to God soul(Shinkon) Merged(Gattai) Godannar)