Mezzo-soprano in the context of Contralto

A castrato (Italian; pl.: castrati) is a male singer who underwent castration before puberty in order to retain a singing voice equivalent to that of a soprano, mezzo-soprano, or contralto. The voice can also occur in one who, due to an endocrinological condition, never reaches sexual maturity.

Castration before puberty (or in its early stages) prevents the larynx from being transformed by the normal physiological events of puberty. As a result, the vocal range of prepubescence (shared by both sexes) is largely retained, and the voice develops into adulthood in a unique way. Prepubescent castration for this purpose diminished greatly in the late 18th century.

The oboe d'amore (Italian for 'love oboe'; (pronounced [ˈɔːboe daˈmoːre]), less commonly hautbois d'amour (French: [obwɑ damuʁ]), is a double reed woodwind musical instrument in the oboe family. Slightly larger than the oboe, it has a less assertive and a more tranquil and serene tone, and is considered the mezzo-soprano of the oboe family, between the oboe (soprano) and the cor anglais, or English horn, (alto). It is a transposing instrument, sounding a minor third lower than it is notated, i.e. in A, so it can also be known as a Mezzo-Soprano Oboe. The bell (called Liebesfuß) is pear-shaped and the instrument uses a crook or bocal, similar to but shorter than that of the cor anglais.

Four-part harmony is music written for four voices, or for some other musical medium—four musical instruments or a single keyboard instrument, for example—for which the various musical parts can give a different note for each chord of the music.

The four main voices are typically labelled as soprano (or treble and countertenor), alto (contralto, countertenor or mezzo), tenor, and bass. Because the human voice has a limited range, different voice types are usually not able to sing pitches that lie outside of their specific range.

In theater, a breeches role or breeches part (also pants role, pants part, trouser role, trouser part, and Hosenrolle) is a role in which a female actor performs in male clothing. Breeches, tight-fitting knee-length pants, were a standard male garment when these roles were introduced. The theatrical term travesti covers both this sort of cross-dressing and also male actors dressing as female characters. Both are part of the long history of cross-dressing in music and opera and later in film and television.

In opera, a breeches role refers to any male character that is sung and acted by a female singer. Most often the character is an adolescent or a very young man, sung by a mezzo-soprano or contralto. The operatic concept assumes that the character is male, and the audience accepts him as such, even knowing that the actor is not. Cross-dressing female characters (e.g., Leonore in Fidelio or Gilda in Act III of Rigoletto) are not considered breeches roles. The most frequently performed breeches roles are Cherubino (The Marriage of Figaro), Octavian (Der Rosenkavalier), Hansel (Hansel und Gretel) and Orpheus (Orpheus and Euridice), though the latter was originally written for a male singer, first a castrato and later, in the revised French version, an haute-contre.

Samson and Delilah (French: Samson et Dalila), Op. 47, is a grand opera in three acts and four scenes by Camille Saint-Saëns to a French libretto by Ferdinand Lemaire. It was first performed in Weimar at the Grossherzogliches (Grand Ducal) Theater (now the Staatskapelle Weimar) on 2 December 1877 in a German translation.

The opera is based on the Biblical tale of Samson and Delilah found in Chapter 16 of the Book of Judges in the Old Testament. It is the only opera by Saint-Saëns that is regularly performed. The second act love scene in Delilah's tent is one of the set pieces that define French opera. Two of Delilah's arias are particularly well known: "Printemps qui commence" ("Spring begins") and "Mon cœur s'ouvre à ta voix" ("My heart opens itself to your voice", also known as "Softly awakes my heart"), the latter of which is one of the most popular recital pieces in the mezzo-soprano/contralto repertoire.

Idina Kim Menzel (/ɪˈdiːnə mɛnˈzɛl/ ih-DEE-nə men-ZEL; née Mentzel; born May 30, 1971) is an American actress, singer and songwriter. Menzel is known for her commanding stage presence, powerful mezzo-soprano voice, and reputation as one of the most influential stage actors of her generation. Having achieved mainstream success across stage, screen, and music, her accolades include a Tony Award and a Daytime Emmy Award.

Menzel rose to prominence as a stage actress in 1996, making her Broadway debut as performance artist Maureen Johnson in the rock musical Rent, which earned her a Tony Award nomination for Best Featured Actress in a Musical. In 2003, she originated the role of Elphaba in the musical Wicked on Broadway, for which she won the Tony Award for Best Actress in a Musical. After leaving the show in 2005, she reprised the role in the musical's original West End production in 2006, becoming the highest-paid actress in West End theatre history. In 2014, Menzel returned to Broadway in the musical If/Then, for which she received a third Tony Award nomination.

Habanera ("music or dance of Havana") is the popular name for "L'amour est un oiseau rebelle" (French pronunciation: [lamuʁ ɛt‿œ̃n‿wazo ʁəbɛl]; "Love is a rebellious bird"), an aria from Georges Bizet's 1875 opéra comique Carmen. It is the entrance aria of the title character, a mezzo-soprano role, in scene 5 of the first act.

A countertenor (also contra tenor) is a type of classical male singing voice whose vocal range is equivalent to that of the female contralto or mezzo-soprano voice types, generally extending from around E₃ to D₅ or E₅, although a sopranist (a specific kind of countertenor) may match the soprano's range of around C₄ to C₆. Countertenors often have tenor or baritone chest voices, but sing in falsetto or head voice much more often than they do in their chest voice.

The nature of the countertenor voice has radically changed throughout musical history, from a modal voice, to a modal and falsetto voice, to the primarily falsetto voice that is denoted by the term today. This is partly because of changes in human physiology (increase in body height) and partly because of fluctuations in pitch.

Kullervo (sometimes referred to as the Kullervo Symphony), Op. 7, is a five-movement symphonic work for soprano, baritone, male choir, and orchestra written from 1891–1892 by the Finnish composer Jean Sibelius. Movements I, II, and IV are instrumental, whereas III and V feature sung text from Runos XXXV–VI of the Kalevala, Finland's national epic. The piece tells the story of the tragic hero Kullervo, with each movement depicting an episode from his ill-fated life: first, an introduction that establishes the psychology of the titular character; second, a haunting "lullaby with variations" that portrays his unhappy childhood; third, a dramatic dialogue between soloists and chorus in which the hero unknowingly seduces his long-lost sister; fourth, a lively scherzo in which Kullervo seeks redemption on the battlefield; and fifth, a funereal choral finale in which he returns to the spot of his incestuous crime and, guilt-ridden, takes his life by falling on his sword.

The piece premiered on 28 April 1892 in Helsinki with Sibelius conducting the Helsinki Orchestral Association and an amateur choir; the baritone Abraham Ojanperä and the mezzo-soprano Emmy Achté sang the parts of Kullervo and his sister, respectively. The premiere was a resounding success—indeed, the definitive breakthrough of Sibelius's nascent career and the moment at which orchestral music became his chosen medium. The critics praised the confidence and inventiveness of his writing and heralded Kullervo as the dawn of art music that was distinctly Finnish. Sibelius's triumph, however, was due in part to extra-musical considerations: by setting the Finnish-language Kalevala and evoking—but not directly quoting—the melody and rhythm of rune singing, he had given voice to the political struggle for Finland's independence from Imperial Russia.

The Andrews Sisters were an American close harmony singing group of the swing and boogie-woogie eras. The group consisted of three sisters: contralto LaVerne Sophia Andrews (1911–1967), soprano Maxene Anglyn Andrews (1916–1995), and mezzo-soprano Patricia Marie Andrews (1918–2013). The sisters have sold an estimated 80 million records. Their 1941 hit "Boogie Woogie Bugle Boy" can be considered an early example of jump blues. Other songs closely associated with the Andrews Sisters include their first major hit, "Bei Mir Bist Du Schön (Means That You're Grand)" (1937), "Beer Barrel Polka (Roll Out the Barrel)" (1939), "Beat Me Daddy, Eight to the Bar" (1940), "Don't Sit Under the Apple Tree (with Anyone Else but Me)" (1942), and "Rum and Coca-Cola" (1945), which helped introduce American audiences to calypso.

The Andrews Sisters' harmonies and songs are still influential today and have been copied and recorded by entertainers such as Patti Page, Bette Midler, Christina Aguilera, The Pointer Sisters, Pentatonix, and others. The group was among the inaugural inductees to the Vocal Group Hall of Fame upon its opening in 1998. Writing for Bloomberg, Mark Schoifet said the sisters became the most popular female vocal group of the first half of the 20th century. They are still widely acclaimed today for their famous close harmonies. They were inducted into the Minnesota Rock/Country Hall of Fame in May 2006.

"Dôme épais le jasmin", often referred to as the "Flower Duet", is a duet for soprano and mezzo-soprano in the first act of the tragic opera Lakmé, premiered in Paris in 1883 and composed by Léo Delibes.

It is sung by the characters Lakmé, daughter of a Brahmin priest, and her servant Mallika, as they go to gather flowers by a river.

Morella Valarino Muñoz (July 29, 1935 – July 15, 1995), was a celebrated Venezuelan mezzo-soprano. She performed as a child under the pseudonym Morella Kenton, and as an adult as Morella Muñoz. She achieved national and international fame as a member of Venezuela's Counterpoint Quintet [es].