The Collaborative International Dictionary of English v.0.48:

Ka \Ka\ prop. n. (Hinduism)
   An unknown god; an epithet of Prajapati and Brahma.
   [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

ka \ka\ n. (Ancient Egyptian Religion)
   A spiritual aspect of the individual, living within the body
   during life, and surviving the body after death. It was
   believed to be one of two spirits inhabiting the body, the
   other being the ba, which deserts teh body at death.
   [PJC]

WordNet (r) 3.0 (2006):

Ka
    n 1: unknown god; an epithet of Prajapati and Brahma