The Romans used the word "viridis" both for green and for blue-green.

Nevertheless, when they wanted to describe more precisely a color, for example when Pliny the Elder had to explain the difference in color between emeralds and beryls, they used expressions like "green like the leaves" or "green like the grass" for green, and "green like the littoral sea" for blue-green.

> The Greek said the sea was green, for example; so did the Romans.

This isn't exactly a surprise; they were both heavily involved with the sea.

English speakers talk about the sea being blue, but that's not because it is blue by the standards of English speakers. It's because most people don't bother to give any thought to the things they say. If you go look at the sea, it is obviously green.

Although Homer speaks of the "wine-dark sea" which is an odd visual picture for us.