A sofa or couch. As far as I can tell, this term is only ever used in Canada and the U.K.; at least, I've never heard it in the U.S.. According to the American Heritage Dictionary, the word is used in Northern California, to which I cannot attest, though having lived there ninety-five percent of my life.

The OED is fairly unhelpful for etymology here, yeilding only that the word derives from the name of a nineteenth century Earl of Chesterfield.

The word can also refer some kind of overcoat, with apparently the same etymology.