Definition of "groundsheet" [ground•sheet]

• A sheet of waterproof material that is spread on the ground, often beneath a tent, upon which a person may sit or sleep. (noun)

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• "There is yet another feature known as groundsheet heat."
• "The groundsheet is now a polyester inner groundsheet which is lightweight and comfortable whilst giving an increased water repellancy of 10,000HH."
• "You see all kindnesses of stunner in the landfall and that's some of the stunner on the groundsheet there."