FROM: http://www.orkneyjar.com/history/brodgar/
The Ring o’ Brodgar takes its name from the nearby farm.
For years, the origin of the placename has been explained as being from the Old Norse brúar-garðr meaning bridge farm. However, there is another intriguing possibility.
Bearing in mind the local pronunciation, broa(d)yeur, could the name actually stem from brúar-jorð – earth bridge? In this case the “earth bridge” could be the entire Ness o’ Brodgar.