from the GNU version of the Collaborative International Dictionary of English
- adj. Relating to the lake of Serbonis in Egypt, which by reason of the sand blowing into it had a deceptive appearance of being solid land, but was a bog.
from The Century Dictionary and Cyclopedia
- Noting a large bog or lake in Egypt, lying between the Delta and the Isthmus of Suez.
Sorry, no etymologies found.
And there, whether it be in the light that beats on God's great throne, or in the serbonian darkness of a hell more horrible than that pictured by Dante -- is the true Heaven.