What is "frithuswith"

Saint Frithuswith (c. 65019 October 727; ; also known as Frideswide, Frideswith, Fritheswithe, Frevisse, or simply Fris) was an English princess and abbess. She is credited with establishing a religious site later incorporated into Christ Church in Oxford — Frithuswith was the first abbess of this Oxford double monastery. Frithuswith was the daughter of a Mercian sub-king named Dida of Eynsham, whose lands occupied western Oxfordshire and the upper reaches of the River Thames. Dida is known to have endowed churches in Bampton and Oxford.