Pradhāna

Pradhāna (devanāgarī: प्रधान) is a Sanskrit adjective meaning "most important, prime, chief or major," and refers to the chief cause of the material nature, the original root of matter, the homogeneous prime matter from which the cosmos is created. According to the Sāṃkhya School, in Pradhana the three Guṇas (sattva, rajas and tamas) are in state of equilibrium.

H. P. Blavatsky defined it as follows:

Pradhâna (Sk.). Undifferentiated substance, called elsewhere and in other schools--Akâsa; and Mulaprakriti or Root of Matter by the Vedantins. In short, Primeval Matter.