Sǽ-draca

According to the Old English Dictionary:

an;

sǽ-draca

m. A sea-dragon, sea-serpent:--Sǽdracan leviathan .i. serpens aquaticus, Hpt. Gl. 424, 55. Gesáwon æfter wætere wyrmcynnes fela, sellíce sǽdracan, sund cunnian, Beo. Th. 2856; B. 1426. sæ-draca