passe-partout /(päs` pär`to͡o")/

passe·-par·tout

passe-partout

n.
  1. That by which one can pass anywhere; a safe-conduct. [Obs.]
  2. A master key; a latchkey.
  3. A light picture frame or mat of cardboard, wood, or the like, usually put between the picture and the glass, and sometimes serving for several pictures.
  4. A strip of adhesive paper or gummed tape used to mount a picture between a piece of glass and a backing.
  5. The method of mounting a picture between a piece of glass and a backing, using a passe-partout{4}.