太极
Tài jí · HSK 7
ultimate
☯ 太极 = 太 (supreme, utmost) + 极 (pole, extreme) = the Supreme Ultimate
The same 太极 names the yin-yang diagram and tai chi: 太 means utmost and 极 means the far pole or limit, so together they mark the ultimate source from which all things split into opposites.
太 — 大 'big' + extra dot 丶
太 originally derived from 大 ('big, person with arms outstretched') with an added stroke to mean 'greatest' or 'too much'. The extra dot intensifies 大, signaling something beyond merely big. Over time it came to mean 'very', 'too', or 'highest'.
极 — wood radical 木 + 及 (jí, phonetic)
极 is a semantic-phonetic compound: 木 (wood) hints at the meaning, since the original sense was the ridgepole — the highest beam of a roof. 及 supplies the sound 'jí'. From 'topmost beam' the meaning extended to 'extreme, utmost, pole', as in 北极 (North Pole).