Âpava (Sk.) Lit. “He who sports in the Water”. Another aspect of Nârâyana or Vishnu and of Brahmâ combined, for Âpava, like the latter, divides himself into two parts, male and female, and creates Vishnu, who creates Virâj, who creates Manu. The name is explained and interpreted in various ways in Brahmanical literature.
Source: H.P.Blavatsky - The Theosophical Glossary