Sometimes people get so technical in creating definitions that they end up defining or categorizing things in a way that flatly contradicts the colloquial definitions of those things. I think that's lame.
One example is the question of whether black is a color. Some people say that it's not because it's the "absence of color", or it's a "shade", which can be used to modify a "color".
But, come on. "Color" is a way to describe what frequencies of light come from an object to our eyes, and which of the light receptors in our retinas react to those frequencies. We experience colors as contrasts to other colors - just try and describe how a color looks in any other way. In that sense, black is definitely a color. It's one of the ways our eyes perceive light bouncing off of things. If someone is wearing a black shirt, and you ask them what color it is, they don't go "Oh my gosh there IS no color!" They also don't try to figure out which primary or secondary color is being reflected the most and then say something like "I think it's a profoundly dark green." They say it's black. And even you developed some ultra-Vantablack shirt and there were no light coming off of it at all, zero is a valid value that something can have. But then again, there's never really zero light.
And that brings me to another point. Some people say that nothing is really black, because black means no light and everything reflects a little light (except a black hole I guess). But dude, that is NOT the definition of black. If it were, it would be totally useless. That's like saying nothing is cold because nothing has a temperature of absolute zero. There are plenty of things that we all look at and say are black. That's the definition of black. It's all relative. All colors are relative. There's no use defining a common word in such a way that it can't actually be applied to anything.