Buddha (Sanskrit) [from the verbal root budh to perceive, awaken, recover consciousness] Awakened, enlightened; one who is spiritually awakened, who has become one with the supreme self (paramatman).
"To become a Buddha one has to break through the bondage of sense and personality; to acquire a complete perception of the real self and learn not to separate it from all other selves; to learn by experience the utter unreality of all phenomena of the visible Kosmos foremost of all; to reach a complete detachment from all that is evanescent and finite, and live while yet on Earth in the immortal and the everlasting alone, in a supreme state of holiness" (TG 64-5).
"A Buddha in the esoteric teaching is one whose higher principles can learn nothing more in this manvantara; they have reached Nirvana and remain there. This does not mean, however, that the lower centers of consciousness of a Buddha are in Nirvana, for the contrary is true; and it is this fact that enables a Buddha of Compassion to remain in the lower realms of being as mankind's supreme Guide and Instructor, living usually as a Nirmanakaya" (OG 33-4).