无极是中国道家观念，是宇宙万物之本源，太极前之状态。

「无极」一词于多部中国古籍，包括道家经典道德经、庄子、儒家经典等都出现过。

《太极图说》是宋代哲学家周敦颐哲学著作，全文只有249字。受《周易·系辞传》启发周敦颐在《太极图说》阐释其宇宙观，「无极而太极，太极动而生阳，动极而静，静而生阴。静极复动，一动一静，互为其根；分阴分阳，两仪立焉。」在其太极图，「无极」为只有外框之圆形，代表阴阳未分、秩序未生前的混沌状态，而后形成万物（宇宙）的本源（太极）。

Wújí 無極 (literally "without ridgepole") originally meant "ultimate; boundless; infinite" in Warring States period (476-221 BCE) Taoist classics, but came to mean the "primordial universe" prior to the Taiji 太極 "Supreme Ultimate" in Song Dynasty (960-1279 CE) Neo-Confucianist cosmology. Wuji is also a proper noun in Modern Standard Chinese usage; for instance, Wuji County in Hebei.