Nappe is a word that is typically used in the context of geology and refers to a sheet-like layer of rock or sediment that has been folded or thrust over other layers. Some common synonyms for nappe include sheet, layer, cover, cloak, and veil. Other related terms that may be used in a geological context include overthrust, tectonic plate, fault line, and fold. In general, these terms are used to describe the movement and positioning of rock layers, and can be helpful for geologists and other researchers studying the earth's history and structure.