ying/yang-opposite or contrary forces yet interconnected and interdependent in the natural world as they interrelate to one another. Many natural dualities are thought of as physical manifestations of the yin-yang concept.
Yin Yang is a philosophical concept expressing the dualism of existence. The Chinese characters of Yin Yang are related to the characters for sun and moon, which are often used to represent masculine and feminine, day and night, and other opposites.
The Chinese terms yin 陰 or 阴 "shady side" and yang 陽 or 阳 "sunny side"