A friend of mine explained that Foss is the Middle English word for river, Dyke is the Viking word for river and Canal is a modern word we all understand. The Fossdyke Canal is so old it has been named 3 times!
The Fossdyke connects the Tidal River Trent at Torksey and the Brayford Pool in the historic City of Lincoln. Lincoln was founded by the Romans, originally Lindum Colonia, and is one of the oldest cities in the country. There is apparently no record of the Fossdyke in Roman history but the canal was evidently there before the Norman Conquest in 1066. The Doomsday Book describes both Torksey and Hardwick as Ports in the time of Edward the Confessor in 1050. Henry I is recorded as having "cut a large canal between Torksey and Lincoln" but there is some debate around whether this was a new canal or making an existing one usable again.
Whoever built the canal it was certainly beneficial for the economy of Lincoln. The railways did their best to stifle its use for commerce and these days it is mainly used by leisure craft and fishermen.