Gambrinus \gam-BRAHY-nuhs\ , noun;
1. A mythical Flemish king, the reputed inventor of beer
This is a tough one because it's a name, so there's no real etymology for it. Also, I'm having a really hard time nailing down information about this king. There is a Wikipedia article here, but it isn't well cited so you can take from it what you will. I tried to look it up the old fashioned way, in an encyclopedia, but I don't have a physical version here at the in-laws' house and the online Encyclopedia Britannica does not have an entry for him. Oh well.
Today's word and the first definition were both taken from Dictionary.com's 'Word of the Day' for Tuesday, December 28