What is "saethryth"

__NOTOC__ Saint Sæthryth (; fl. 660s), also called Sedrido, Sethrida or Saethrid, was the stepdaughter of king Anna of East Anglia, who became a Benedictine nun at the abbey of Faremoutiers-en-Brie, Gaul under its foundress Saint Burgundofara, whom she succeeded as abbess. Saints Seaxburh, Ethelburga, Etheldreda and Withburga were half-sisters.