passe-partout
passe-partout (pas` par`to") , noun
[French, from passer to pass + partout everywhere.]
1.
That by which one can pass anywhere; a safe-conduct. [Obsolete] — Dryden
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}.
Also: Passe partout