Taegeuk (in Kukkiwon/WTF Taekwondo) refers to a set of poomsae or forms used to teach Kukkiwon/WTF taekwondo. A form, or poomsae (also spelled pumsae or poomse) is a defined pattern of defense-and-attack motions. Outside of the context of taekwondo, the word taegeuk (the Korean pronunciation of Taiji / T'ai Chi) refers to the Taoist principle of the "unity of opposites" (yin and yang). Taegeuk is also the name of the red and blue circle used in the flag of South Korea.