#choir

• Altist — A singer with an alto voice (especially a boy or a man using falsetto) or a musician who plays an alto instrument, such as a viola player or a performer on the alto saxophone. As an adjective, it describes a timbre, composition, or instrumental register specific to the alto range.
• Female alto — A female singer whose voice falls within the alto register (pitched between soprano and tenor or contralto) or a woman who plays an instrument in the same acoustic range (viola, alto saxophone).
• Alto — A deep female voice or a boy's voice pitched in a register between soprano and tenor (also called contralto); a musical part or score written for this range. It also designates musical instruments with a timbre corresponding to this range (e.g., alto saxophone, alto flute) or, as an adjective, describes such an acoustic register.
• Antiphonary — A liturgical book used in the Christian Church (especially in the Roman Catholic and ancient Byzantine traditions) containing the antiphons, verses, psalms, and hymns designated to be sung alternatively by two choirs throughout the liturgical year.
• Antiphonal — Insulating against noise or damping sound vibrations; pertaining to soundproofing or acoustic reduction. In liturgical or religious music (theology), the term describes a hymnal structure or a mode of vocal performance based on the symmetrical alternation and dialogue between two separate choirs.
• Antiphony — A system of musical or liturgical performance characterized by the alternate singing of two choirs or a soloist and a choir responding successively; a genre of church chant based on this dialogue structure, used since antiquity and consolidated in Byzantine and Gregorian liturgies.
• Aurocor — A rare or literary term formed by composition (auro + cor), utilized in ancient poetic texts, religious writings, or ornamental descriptions to designate a brilliant choir, a gathering of divine voices, or a celestial suite shrouded in golden light. As an adjective, it describes something possessing a golden crown or a pure luminous aura.