Fífel-dór

According to the Old English Dictionary:

es;

fífel-dór

n. Monster or terror-door, the river Eider, the boundary between Holstein and Schleswig; monstrōrum mărīnōrum porta :-- Bí fífeldóre by the monster-door, Exon. 85a; Th. 321, 8; Wíd. 43. fifel-dor