The term 'Negative Side' can be represented by the crossword solution YIN, which is a three-letter word. YIN is a Chinese philosophical concept that is associated with darkness, femininity, and the moon. It is often used to describe the negative aspects of life, such as sorrow, pain, and death. In contrast, YANG is the opposite of YIN and is associated with light, masculinity, and the sun. Together, YIN and YANG represent the duality of life and the balance between the two.