Etheldreda combines the Old English æthel (noble) and thrȳth (strength) — "noble strength." Saint Etheldreda (c. 636-679) was the East Anglian princess who founded Ely Abbey — one of the most powerful Anglo-Saxon women.
The name Audrey is the modern descendant of Etheldreda.
Etheldreda reduces to seven — the number of Anglo-Saxon saint.