
• (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.
Found on 
http://thinkexist.com/dictionary/meaning/serbonian/
Ser·bo'ni·an  adjective  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. Found on 
http://www.encyclo.co.uk/webster/S/71
  No exact match found.