cho·ris·ter 
(kôrĭ-stər, kŏr-)
(kôrĭ-stər, kŏr-)n.
1. A singer in a choir, especially a choirboy or choirgirl.
2. A leader of a choir.
[Middle English queristre, from Anglo-Norman *cueristre, from Medieval Latin chorista, from chorus, chorus, from Latin, choral dance; see CHORUS.]