Source : Webster's Revised Unabridged Dictionary (1913)

Montre \Mon"tre\, n. [F., show, show case, organ case.]
   1. (Organ Building) A stop, usually the open diapason, having
      its pipes ``shown'' as part of the organ case, or
      otherwise specially mounted.

   2. A hole in the wall of a pottery kiln, by which the state
      of the pieces within can be judged.