Ap, Apas, Apah (Sanskrit) [from ap water] Watery, water; in the plural [apah, apas the waters], considered as feminine deities and mothers from whom all issue forth. Cosmically apah or apas are the waters of space, out of which the universe is produced. "Apah (the waters) assume different forms of this earth, this atmosphere, this sky, the mountains, gods and humans (deva-manushyah), beasts and birds, grass and trees, animals together with worms, flies, and ants. Apah (water) indeed is all these forms" (ChU 7:10, 1).
Apas or Ap is the name of the rakshasa associated with the month Karttika (October) (VP 2:10, p.5n); Apas is listed also as a prajapati of the second manvantara, son of Vasishtha (VP 3:1, n1).