diaphragm vs pellicle

diaphragm

noun
  • A flexible membrane separating two chambers and fixed around its periphery that distends into one or other chamber as the difference in the pressure in the chambers varies. 

  • In a speaker, the thin, semi-rigid membrane which vibrates to produce sound. 

  • A thin opaque structure with a central aperture, used to limit the passage of light into a camera or similar device. 

  • Any of various membranes or sheets of muscle or ligament which separate one cavity from another. 

  • A floor slab, metal wall panel, roof panel or the like, having a sufficiently large in-plane shear stiffness and sufficient strength to transmit horizontal forces to resisting systems. 

  • A contraceptive device consisting of a flexible cup, used to cover the cervix during intercourse. 

  • In mammals, a sheet of muscle separating the thorax from the abdomen, contracted and relaxed in respiration to draw air into and expel air from the lungs; also called thoracic diaphragm. 

  • A permeable or semipermeable membrane. 

verb
  • To reduce lens aperture using an optical diaphragm. 

  • To act as a diaphragm, for example by vibrating. 

pellicle

noun
  • A thin plastic membrane used as a beam splitter or protective cover. 

  • A skin or coating of proteins on the surface of meat to be smoked, improving the surface adhesion. 

  • The growth on the surface of a liquid culture. 

  • The skin of a mushroom cap. 

  • A thin skin or film. 

  • The outermost layer of a mushroom, often used only for a surface that is viscid and easily peels off. 

  • Cuticle, the hard protective outer layer of certain life forms. 

  • The photosensitive emulsion of photographic film. 

How often have the words diaphragm and pellicle occurred in a corpus of books? (source: Google Ngram Viewer )