bivvybag noun1 •A lightweight, durable, waterproof bag, somewhat larger than a sleeping bag, that acts as an alternative to a tent.But while De Quincey came up with a prototype for a one-person tent, Stevenson invented the bivvybag, 'a sort of long roll or sausage, green waterproof cart-cloth without and blue sheep's fur within.' — 2011 formsbivvybags
