groundsheet n 1: a waterproofed piece of cloth spread on the ground (as under a tent) to protect from moisture [syn: {groundsheet}, {ground cloth}]
groundsheet \ground"sheet`\ (ground"sh[=e]t`), n. a piece of waterproofed cloth spread on the ground (as under a tent) to protect the occupants from moisture. Syn: ground cloth. [WordNet 1.5]