(Sitr). Curtain or veil or covering or concealment. That which veils you from that which will make 'you' disappear. Also known as the 'wrapping of the universe'. In reality, Allah does not place anything behind a curtain. That which covers the Truth is either 'your ignorance' or 'your self' or your attachment to things. The removal of these covers reveals the Truth which was never veiled in the first place.