buddhiḥ
The intellect; reasoning; knowledge; recognition; will; deliberate thought.
In Vedanta
The aspect of the antaḥkaraṇam whose function is determination (niścaya). Buddhi resolves the doubt raised by manas and arrives at a conclusion. It is the seat of knowledge and decision. In Vedānta, self-knowledge takes place in the buddhi — when the buddhi, informed by the teaching, recognizes 'I am Brahman,' that is mokṣa. The buddhi is the closest upādhi to ātmā.