taijitu; yin-yang symbol; cosmic dual forces symbol
Refers to the classic circular symbol representing yin and yang, often used in Taoist and Confucian philosophy.
from Chinese
The taijitu represents the harmony of yin and yang.
From Chinese 太極圖 (tàijítú), composed of 太極 'supreme ultimate' and 圖 'diagram'. The term entered Japanese as a loanword.