The term has two meanings. First, it refers to the state of one whole mass that existed before the universe took shape, often said to exist before qi (vital force) emerged. The multitude of organisms on earth all emanated from this state. Second, it refers to Chaos, king of the Central Region in a fable in Zhuangzi. According to the fable, Chaos had no eyes, nose, mouth or ears. Shu, king of the South Sea, and Hu, king of the North Sea, drilled seven apertures into Chaos and killed him. Zhuangzi used this story to show the state of chaos of the world in which there is neither knowledge or wisdom, nor distinction between good and evil.
Those who commented on The Book of Changes said, “Before qi (vital force) appeared, the world was in a state of formless chaos.” (Wang Chong: A Comparative Study of Different Schools of Learning)
The king of the South Sea was called Shu, the king of the North Sea was called Hu, and the king of the Central Region was called Chaos. Shu and Hu often met in the territory of Chaos, who treated them very well. They wanted to repay his kindness, and said, “Every man has seven apertures with which to hear, to see, to eat and drink, and to breathe, but Chaos alone has none of them. Let’s try and bore some for him.” They bored one aperture on Chaos each day, and on the seventh day Chaos died. (Zhuangzi)