Where the Arnold name comes from

Arnold is a surname found in both Germany and England. It goes back to the Germanic name Arnuwald, built from arô, meaning eagle, and waldą, meaning might. The eagle half shares its origin with the English word erne. Latin named people after the eagle too, in the given name Aquila and the feminine Aquilina. The name reached England in a French form, carried over by the Normans, and as a surname it began as a patronymic, marking a family descended from a father called Arnold.

One English branch took the name to Portugal with William Arnold, a knight who accompanied Queen Philippa of Lancaster there and oversaw her household. In Portugal he became Guilherme Arnaut, and the surname came to be written Arnao.