A mezzo-soprano (meaning "medium" or "middle" "soprano" in Italian) is a female singer whose range lies between the soprano and the contralto, usually extending from the A below middle C to the A two octaves above (i.e. A3-A5 in scientific pitch notation, where middle C = C4). While mezzo-sopranos generally have a heavier, darker tone than sopranos, the mezzo-soprano voice resonates in a higher range than that of a contralto. The terms Dugazon and Galli-Marié are sometimes used to refer to light mezzo-sopranos, after the names of famous singers. A castrato with a mezzo-soprano range was also called a mezzo-soprano castrato or mezzista.
Mezzo-sopranos typically sing secondary roles in operas, with the protagonist in Bizet's Carmen and Rosina in Rossini's Barber of Seville as the most notable exceptions. Typical roles for mezzo-sopranos include witches, nurses, and wise women such as Azucena in Verdi's Il Trovatore; trouser role (male characters played by female singers) such as Cherubino in Mozart's Le Nozze di Figaro; and villains and seductresses such as Amneris in Verdi's Aida. Mezzo-sopranos are also well represented in baroque music, early music and baroque opera, they are sometimes cast in soubrette roles if a more dramatic sound is desired, and some of the lower-tessitura soprano roles can be sung by mezzos as well. In current operatic practice, contraltos are also counted as mezzo-sopranos. For the different types of mezzo-sopranos, see voice type.
Some roles designated for lighter soubrette sopranos are sung by mezzo sopranos, who often provide a fuller, more dramatic quality. Such roles include Despina in Mozart's Così fan tutte and Zerlina in Mozart's Don Giovanni. Mezzos also sometimes play dramatic soprano roles such as Santuzza in Mascagni's Cavalleria rusticana, Lady Macbeth in Verdi's Macbeth, and Kundry in Wagner's Parsifal.