in Mesopotamian mythology, the male and female principles, the twin horizons of sky and earth. Their parents were either Apsu (the watery deep beneath the earth) and Tiamat (the personification of salt water) or Lahmu and Lahamu, the first set of twins born to Apsu and Tiamat. Anshar and Kishar, in turn, were the parents of Anu (An), the supreme heaven god.