REPOUSSÉ is a decorative metal technique that you see on many antiques. In a nutshell, it's hammering metal from the reverse side to create a relief design on the outside, as seen here on the top and border of an antique Flemish mirror:
This gives a dramatic decorative effect to the mirror:
List price: $42,500 USD
It's pronounced "ruh poo SAY".
Here's another excellent example of repoussé, this time on a pair of Italian 17th century copper-clad wall sconces:
List price: $14,0000 USD
Can you see how the leaf motif directly below the drip pan (called the bobeche, and pronounced "bo BESH") has been hammered from the inside out?
Some people confuse repoussé with REPOUSSOIR (pronounced "ruh poor SWAHR") but they're very different. Repoussoir is when an object or figure in a picture is put in the front of the scene to help direct the eye into the composition.
Vermeer uses repoussoir in his 17th century masterpiece, "The Art of Painting:"
Note how he depicts the draped curtain in the foreground to draw your eye into the scene and to create the illusion of perspective-this is repoussoir.