E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
(Anglo-Saxon, eorl, a man of position, in opposition to ceorl, a churl, or freeman of the lowest rank; Danish, jarl). William the Conqueror tried to introduce the word Count, but did not succeed, although the wife of an earl is still called a countess.
The sheriff is called in Latin vice-comes, as being the deputy of the earl or comés, to whom the custody of the shire is said to have been committed.Blackstone: Commentaries, book i. chap. ix. p. 339.