When trying to do some research on this word, every time I typed "eagre" into the search engine, the results always came up with either eager or eagle.  It would give me the definition of eagre, but when I looked for any other facts about the word, I always ended up looking at  results for eager or eagle. 

I looked at the definition and picture and said to myself, “Aren’t these tidal bores that occur with the incoming tide on some rivers around the world?” Good ol’ Wikipedia came to the rescue once again.

The bore on the River Nene (NEN or NEEN, depending on where you are along its course) had an Eagre of one to four feet in height. The river begins in Northamptonshire and flows 105 kilometers to The Wash and the North Sea in Lincolnshire. The eagre was eliminated with navigation improvements.

The Trent Aegir is the bore on the River Trent, England. The bore on River Ouse, Yorkshire, is also called an aegir.

The River Severn bore, at up to 2 meters (7 feet) is the highest in the United Kingdom.

The world’s largest bore occurs on the Qiantang River, China, at up to 9 meters (30 feet) traveling at 40 km/h (25 mph).

In the United States, the bore in Turnagain Arm of Cook Inlet, Alaska, is up to 2 meters (7 feet) and 20 km/h (12 mph).

Some bores are high and fast enough to permit recreational surfing.