1) A sheet of material used to prevent a spill of light in a lantern or in part of a set. 2) A panel in a loudspeaker cabinet designed to reduce back interference noise by isolating the front and rear of the loudspeaker diaphragm. 3) A panel in an auditorium positioned so as to reduce sound reflections and improve the acoustics of the space.4) What most of this jargon will do to any non-technical theatrical type.