A ground cloth is a piece of waterproof material that you put on the ground to sleep on when you are camping.
[US]regional note: in BRIT, use groundsheet
ground cloth in American English
noun
1.
groundsheet
2.
a covering, usually of canvas, for the floor of a stage
Word origin
[1915–20]This word is first recorded in the period 1915–20. Other words that entered Englishat around the same time include: collage, conditioning, markup, soviet, stockpile