Buddhi
Buddhi is a Sanskrit term used in Indian philosophy and psychology to denote the intellect or discriminating faculty of the mind. Etymologically, it derives from budh- “to know,” and is commonly translated as intellect, understanding, or reason. In many systems, buddhi is considered one of the inner instruments that compose the antahkarana (the “inner organ”) alongside manas (the mind), ahaṃkāra (ego), and citta (memory or impression).
In classical Samkhya and Yoga philosophy, buddhi is the rational faculty that evolves from mahat (cosmic intellect).
In Vedanta, especially in Advaita traditions, buddhi is viewed as the instrument through which true knowledge
In other schools such as Nyaya, buddhi is regarded as the instrument of knowledge—one’s capacity for inference,