In English, name Ernestine means – Feminine form of Earnest: A variant spelling of the German Earnest, meaning serious determined, earnestness or vigor, from the Old German Ernust. Famous bearer: The hero of Oscar Wildes comedy The Importance of Being Earnest.. Other origins for name Ernestine include – English, German, German. Name Ernestine is most often used as a girl name or female name.