Augusta was the feminine form of the title Augustus. It was usually given to the wives or relatives of the Roman Emperors. In the 3rd century, "Augustae" could also receive the titles of "Mater castrorum" and "Mater patriae". Wikipedia
The definitive Wikipedia entry for Augusta. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Augusta_%28honorific%29