ACT
A portion of an opera designated by the composer, which has a dramatic structure of its own.

ARIA
A solo piece written for a main character which focuses on the character's emotion.

ASIDE
A secret comment from an actor directly to the audience that the other characters cannot hear.

BARITONE
The male singing voice that is higher than bass but lower than tenor.

BASS
The lowest male singing voice.

BEL CANTO
Italian phrase literally meaning 'beautiful singing.' A traditional Italian style of singing emphasizing tone, phrasing, coloratura passages, and technique; also the operas written in this style.

BUFFO
From the Italian for 'buffoon'. A singer of comic roles (basso-buffo) or a comic opera (opera-buffa).

CADENZA
A passage of singing, often at the end of an aria, which shows off the singer's vocal ability.

CHOREOGRAPHY
The act of setting movement to music to create a dance.

CHORUS
A group of singers who portray servants, party guests, or other unnamed characters; also the music written for them.

COLORATURA
Elaborate ornamentation of music written for a singer using many fast notes and trills.

COMPOSER
The person who writes the music.

CONDUCTOR
The leader of the orchestra sometimes called maestro.

CONTRALTO
The lowest female singing voice.

CRESCENDO
A build in the volume or dynamic of the music.

DESIGNER
The person who creates the lighting, costumes or sets.

DIRECTOR
The person who instructs the singer-actors in their movements on-stage and in the interpretation of their roles.

DUET
Two people singing or playing together, or the music written for two performers.

ENSEMBLE
Two or more people singing at the same time, or the music written for such a group.

FINALE
The last musical number of an opera or the last number of an act.

INTERLUDE
A short piece of instrumental music played between scenes or acts.

KEY
The specific tonality of a piece of music, indicating the precise pitch which is to serve as the tonal center.

LIBRETTO
The text or words of an opera.

LYRICS
The sung words or text of a musical comedy or operetta song.

MELODY
The tune of the music.

MEZZO-SOPRANO
The middle female singing voice, lower than soprano, but higher than contralto.

OPERA
Italian for 'the work'. A libretto acted and sung by one or more singers to an instrumental accompaniment. In short: words plus music plus staging

ORCHESTRA
The group of instrumentalists or musicians who, led by the conductor, accompany the singers.

ORCHESTRATION
The art of writing for the orchestra. Decisions about what instruments should play which parts of the music can affect the sound of a composition a great deal.

OVERTURE
The orchestra's introduction to an opera that shows the mood or tone of the opera (French: ouverture; German: ouverture; Italian: sinfonia).

PITCH
The highness/lowness of a sound or tone.

PRINCIPAL
A major singing role, or the singer who performs such a role.

QUARTET
Four singers or the music that is written for four singers. Also quintet, sextet, etc

RECITATIVE
The sung words which often come before an aria or ensemble. The purpose of recitative is to advance the plot.

SCORE
The written music of an opera or other musical work.

SERENADE
A piece of music honoring someone or something, an extension of the traditional performance of a lover beneath the window of his mistress.

SOPRANO
The highest female singing voice.

TEMPO
The speed of the music.

TENOR
The highest adult male singing voice.

TRILL
Very quick alternation of pitch between two adjacent notes. See coloratura.

TRIO
An ensemble of three singers or the music that is written for three singers.