…when we have “chorus”, “choral” and “chorale” in the same word family? How did the “cho” become “qui” in “choir”? It seems wrong, but there must be a good reason. Anyone know what it is?
Oddly enough, the word used to be spelled “quire”:
[Middle English quer, quire, from Old French cuer, from Medieval Latin chorus, from Latin …]
The question now becomes "why does the word once spelled ‘quire’ come to be spelled ‘choir’ " ?
There was at one time a movement towards the respelling of perfectly good English words to reflect an assumed etymological relationship with Latin. Two common example would be debt and island, which had the silent letters tacked on well after their pronunciations in English had been established. The respelling of “quire” as"choir" is more of the same.
I should make clear that “choir” does indeed have an etymological relationship with Latin chorus. However, the French form cited above was an intermediary, and the word “quire” had been around a good while as a fully assimilated English word before it ecame fashionable for it to be spelled “choir”.
bordelond:
And when it was, it was pronounced “queer”, just to add to the confusion.
O, the rising of the sun,
The running of the deer
The playing of the merry organ,
Sweet singing in the quire*
In that case, I have to wonder if the change in pronunciation proceeded the change in spelling, or vice versa. Or whether they happened simultaneously.
Ah, so Ronnie Barker was just being archaic, not erroneous, in his Christmas appeal for funds for the Loyal Society for the Prevention of Pismonouncriation.
R.I.P., Ronnie.
WAG So the quire can sing in chorus? Chorus singing in quire sounds odd/strange!
My uncle Hugo said he went to choir practice twice a week for three months, but it didn’t do a thing for his bad back. 
Who else here has actually had reason to use the modern word ‘quire’ in writing?
Only when using the BCP inspired phrase “in quires and places where they sing” in the odd choral newsletter. I was also a member of a mediaeval group for a while that used that spelling: the Quire of the Holy Rood.
Like a writing quire?
I’d never heard the quire pronunciation before, and I’ve always thought of myself as a cunning linguist.