Query: Why the plural in Spanish "Buenas dias," etc.? (OT)

[Peter Richardson]

> It's "Buenos dias" (acute accent on the i, "di/as") not "buenas".  "El di/a"
> is one of the rare exceptions to the rule that a noun ending in -a is
> feminine.

...and probably because its Latin predecessor is masculine--the only
masculine noun, I believe, in the 5th declension.

PR