My book says the setence "litteris victoriam nuntiant" means they report the victory by means of a letter. Why is letter pluralized in this sentence? Thank you.

Answer 1

It would be they reported the victory by letters

Answer 2

I posted about this once before.

In the singular, "littera" means a letter of the alphabet, such as a, b, c, etc.

In the plural, "litterae" (or whatever case you'd be using) can mean letters of the alphabet or it can mean a letter (one epistle).

So the interpretation is fuzzy.