Blue, says my Collins dictionary, is a colour which has a wavelength from 490 - 445 nanometres.
I have no real idea what that means from a practical point of view, but I know that a Russian speaker wouldn't agree with the figures because to a Russian what I call light and dark blue are completely different colours.
A Turkish, Mongolian, Italian or Hebrew speaker won't agree with the figures, either, because those language make similar sorts of distinctions.
A Vietnamese speaker will be puzzled, too. To him xanh is the colour of both the sky and the leaves on a tree. Kurdish does the same sort of thing with şîn.
To the Chinese qīng can mean what we call blue, or it can mean green, or even black.
A Welsh speaker has the word glas, which can be the colour of the sea, or of the grass, or of silver. (Irish uses glas, too, but that colour is the green of plants.)
The Japanese describe 'go' traffic signals as ao, which also is used to mean what I call blue; and, just to confuse things further, in Arabic poetry the sky is sometimes called samā’, which means the green one.
How about that?
Every language leading to a different world.
Word To Use Today: blue. Blue comes to us through French and various Germanic languages and is related to the Latin flāvus, which means yellow.