To sing in a choir; SYN. chorus.

ETYM Old Eng. quer, Old Fren. cuer, French choeur, from Latin chorus a choral dance, chorus, choir, from Greek, orig. dancing place.
(Homonym: choir).
1. A chorus that sings as part of a religious ceremony.
2. A family of similar musical instrument playing together; SYN. consort.
3. The area occupied by singers; the part of the chancel between sanctuary and nave.

In a cathedral, the area used by the choir, usually part of the chancel.

Body of singers, usually of sacred music, of more than one voice to a part, whose members are able to sight read music and hold a melody. A traditional cathedral choir of male voices is required to sing responses, hymns, and psalms appropriate to the church calendar.
The choir was the principal medium for the development of Renaissance polyphony, with instruments initially reading from vocal parts and only subsequently evolving distinct instrumental styles. The Venetian antiphonal style of Monteverdi and Gabrieli treats voices and instruments as opposing choirs. During the 19th century choir festivals became a popular feature of musical life, promoting mixed-voice choral singing by amateur groups.