Are the rules of calculus shrouded in mystery to you? The verb shroud means to hide or cover something or someone. The fog might shroud the valley, or that long-sleeved, ankle-length dress might shroud the tan you worked so hard on in Mexico over Christmas break.
It used to be that corpses were dressed for burial not in person’s best outfit but in a shroud — a garment, often white, made to cover the body. When ghosts, zombies or mummies are depicted in rags, they are wearing the remains of their burial shrouds. If you should hide from them by covering yourself with an abandoned tarp, you will be shrouding yourself from sight.