How did the kingdom of Oz get its name?

Although some biographers believe the story of Oz’s naming to be as fanciful as the tales themselves, author L. Frank Baum claimed that he was inspired by a file cabinet marked O–Z.

Other suggested derivations include:

a variation on Uz, Job’s house;

a variation of children’s oh’s and ah’s;

and a variation of Boz, the pseudonym for Charles Dickens, one of Baum’s favorite authors.