bg means bluish green, being a green having more blue than yellow in its composition. Color Value C. R. Clifford. The sound of such a final a is in all three languages the same as that of the second o in “promote”; thus, the bg. Encyclopaedia Britannica, 11th Edition, Volume 3, Slice 5 Various. The above remarks show that O. has, on the whole, preserved the original sounds of the various letters better than bg.