Merriam-Webster Collegiate Dictionary - choir

 I. noun  Etymology: Middle English quer, from Anglo-French queor, from Medieval Latin chorus, from Latin, chorus — more at chorus  Date: 14th century  1. an organized company of singers (as in a church service)  2. a group of instruments of the same class a brass ~  3. an organized group of persons or things  4. a division of angels  5. the part of a church occupied by the singers or by the clergy; also the part of a church where the services are performed  6. a group organized for ensemble speaking  II. intransitive verb  Date: 1596 to sing or sound in chorus or concert