1911 Encyclopædia Britannica/Duenna
DUENNA (Span. dueña, a married lady or mistress, Lat. domina), specifically the chief lady-in-waiting upon the queen of Spain. The word is more widely applied, however, to an elderly lady in Spanish and Portuguese households (holding a position midway between a governess and companion) appointed to take charge of the young girls of the family; and "duenna" is thus used in English as a synonym for a chaperon.