Pitri

Pitri, pit′rē, n.pl. the deceased ancestors of a man: in Hindu mythology, an order of divine beings inhabiting celestial regions of their own, and receiving into their society the spirits of those mortals for whom funeral rites have been duly performed.

It does certainly look as though Dyaus, the sky, had become personal and worshipped only after he had been raised to the category of a Pitri, a father; and that this predicate of Father must have been elaborated first before it could have been used, to comprehend Dyaus, the sky, Varuna, and other Devas.

Again, the conception of patrons or Pitris to each family and tribe naturally led to the idea of a Providence over all; and so the Pitri begat the Deva.

The fire in the house denoted the ancestor, or pitri, and in turn the serpent was revered as a living fire, and so an appropriate symbol of the First Father.—A.

Its object was in fact to raise the departed to the rank of a Pitri, and this had to be achieved by Srâddha offerings continued during a whole year.