11. ''Apsu''
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*History 8 Mesopotamia Vocabulary
Apsu is a Sumerian word, and apparently the word "abyss" was derived from it. Apsu was the edge of a great fresh water sea that stretched out to the south. According to the Sumerians Apsu was the dwelling places of the god of waters, Enki. Apsu was also a god, representing the deep waters, hence the word abyss. [1] -Evan Hammerman
Cf Manual Page 73