I thought that’s white, because in color theory, white is the absence of color. For example, Mont Blanc was so named because of that.
Another example is that African Americans are called black, or people of color, not people of no color.
In my view, black, white, and different shades of gray, are all colors, even though they are not the primary ones. But we can differ, as long as we know what color, or not color, one refers to.