The term 'Half of the Tai Chi Symbol' refers to the Yin, which is a three-letter word. Yin is one of the two fundamental principles in Chinese philosophy and is often symbolized by the Tai Chi symbol. Yin is associated with darkness, femininity, and the moon, while Yang is associated with light, masculinity, and the sun. Together, Yin and Yang represent the duality of the universe and are believed to be complementary forces that interact to form a whole.