(Donna). A lady deceived by Don Giovanni, who deluded her into a liaison with his valet, Leporello. (Mozart's opera, Don Giovanni.)
A lady who loved Ernani, the robber-captain, and head of a league against Don Carlos, afterwards Charles V. of Spain. She was betrothed to Don Ruy Gomez de Silva, an old Spanish grandee, whom she detested, and Ernani resolved to rescue her; but it so happened that the king himself fell in love with her, and tried to win her. When Silva learned this, he joined the league; but the king, overhearing the plot in concealment, arrested the conspirators. Elvira interceded for them, and the king granted them a free pardon. When Ernani was on the point of wedding Elvira, Ernani, being summoned to death by Silva, stabbed himself. (Verdi's opera of Ernani.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894