The shroud of concealment, according to Golden Dawn teaching, is a shell of etheric substance built up around the magician by intensive ritual work to prevent others from perceiving him. The creation of the shroud of concealment is fundamental to the Order’s method of magical invisibility, and closely related to the odic shield and other magical systems. A.G.H.
Greer, John Michael.The New Encyclopedia of the Occult. St. Paul, MN, Llewellyn Worldwide. p. 437