What's mean "Choir" ?

Usually, I don't hear the word "choir". Could you tell me the meaning ? (From Nyao / lives in Nara. age 22)

Gamera:	The original meaning is "Chancel of church". Is that right ?
Nasu-chan:	That's right. So the choir and chorus group were called "choir" by music trade.
Gamera:	I told that I belomgs to choir to my friend. She said "Are you belongs to chorus group aren't you ?"
Nasu-chan:	What ??? I don't think that you can singing. She have to jedge by personality....
Gamera:	The original meaning turn to "Ensemble by same kinds of music instruments".
Nasu-chan:	Is it enough for you, Mr. Nyao ?