Bivvy

a domed shaped tent that has a large opening at the front so that you can fish from under it. Mainly used by carp or specimen anglers
Found on http://www.fish-uk.com/dictionary.htm

Bivvy

A very small tent designed for one person only, used purely for sleeping in in emergency situations. Single skinned, made with Nylon and GORE-Tex or a similar mebrane and DWR coating, Bivvis are resistant to water and snow, but are still at risk of dampness caused by condensation forming on the inner layer.
Found on http://www.gooutdoors.co.uk/glossary

Bivvy

Bivvy is British slang for a small tent or shelter.
Found on http://www.probertencyclopaedia.com/browse/ZB.HTM
No exact match found