Upanishads (Upan`ishads) (Instructions), a voluminous heterogeneous collection of treatises connected with the Vedas, and the chief source of our knowledge of the early metaphysical speculations and ethical doctrines of the Hindus; they are to a great extent apocryphal, and are posterior to the rise of Buddhism.
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Unyoro * Upas Tree