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.
The Century Dictionary and Cyclopedia
Noting a large bog or lake in Egypt, lying between the Delta and the Isthmus of Suez.
Word Usage
"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."