Adela is from the Old German adal (noble). Adela of Normandy (c. 1067-1137) was the daughter of William the Conqueror and Matilda of Flanders — Countess of Blois, mother of King Stephen of England, and important patron of the Cluniac reform.
Adela Rogers St. Johns was the iconic American journalist (1894-1988).
Adela reduces to one — the number of Norman noble.