Black is not a color, strictly speaking. It is the absence of all color and often misunderstood. A black tie dinner is very formal and elegant. Women can wear that "must have little black dress" to the black tie dinner. Yet the bad guys wear black hats. Black symbolizes death in some cultures. Native Americans thought black was good because it was the color of soil, which gives life.
When people speak of opposites, it is usually in terms of black and white. Black absorbs all aspects of light. While white reveals, black conceals. It has come to mean hidden, fearful or bad experience. It is linked to the unknown or the unseen.