An air de cour is a type of Baroque song. If I’m talking about several of these, would I say “we played some airs de cour”?
Frankly, and especially since this is a foreign phrase (French), the thing that seems most natural to me in speaking it aloud is actually to say “air de cours”.
I realize this is not correct in French speech, but in English, it wouldn’t sound right at all to say “airs de cour”, particularly since the “de cour” means nothing to most saxophones.
Of course, I would never say “I bought some jar of chocolates”, but that’s because the “of chocolates” means something in English, so it would sound wrong and be wrong.
It seems to me that in pluralizing a foreign noun phrase, it may as well be treated as a single word when spoken aloud, with the s added at the end.
Is there a rule on this?