(adjective) - From the French, faux literally means "false" or "artificia.l" In other words, you're not looking the genuine article. To be blunt, faux(-anything) in art is fake(-anything).
One can use the adjective "faux" in front of just about any man-made material created to simulate something organic. Lots of decorative objects utilize faux materials. Faux bois looks like wood, faux porphyry looks like stone, faux pearls look like real pearls, faux leather doesn't look a thing like leather and faux fur looks frightful, but was a lot of fun in the 60s. Eye of the beholder, and all that.
However! The state of faux-dom is not necessarily a bad thing. Real marble walls, for example, are problematic in terms of your average domestic construction. A faux marble painted finish can closely resemble marble, thereby impressing the neighbors and offering the added benefit of avoiding a roof collapse.