(The name of) any of three ancient dykes or embankments in Norfolk, raised to keep out fen water.
The Old Powdyke was raised 1223; it ran from west to east separating Marshland from Bardolph Fen. The New Powdyke was begun in 1423; it ran along the north brink of Well Creek, forming the southern boundary of Stow and Downham Fen. There was also a Little Powdyke, at the west end of the Old Powdyke. See further W. Dugdale Hist. Imbanking & Drayning Fenns (1662) liv..
Origin
Middle English; earliest use found in Patent Roll, 21 Edward I. From a first element of unknown origin + dike.