A thin membrane is a very thin layer of material that can be used to separate two substances. The term 'thin membrane' can be broken down into two words: 'FILM' and 'PELLICLE'. FILM is a four-letter word that refers to a thin layer of material, such as plastic or celluloid, that is used to create a barrier between two substances. PELLICLE is an eight-letter word that refers to a thin membrane, usually made of protein, that covers the surface of a cell. Both FILM and PELLICLE are used in a variety of applications, including medical, industrial, and scientific research.