[sә:'bәunjәn]
adj.
(古埃及北部)塞波尼斯(Serbonis)大沼泽的

Serbonian \Ser*bo"ni*an\, a.
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.

A gulf profound as that Serbonian bog . . .
Where armies whole have sunk. --Milton.