A container, often made of porcelain, and covered, for purposes of elimination... in short, for pissing and crapping in. Often mistaken (in antique shops) for soup tureens, much to the discomfiture of dinner guests of the unwary buyer. Chamber pots have a long and intreguing history, and many designs have been popular over the years... the classic one handle-and-cover, the six-handled (no groping), etc. Most often found under beds and still used to some extent in the military, they can also be kept in "commodes" -- small chests for discreet (or emergency) use, especially in semi-public areas, for instance right outside a dining room.
Traditionally, they're often inscribed with the motto "Pass it over here, dear" (which, I guess, is supposed to refer to the intimate needs of a loving couple) and other humorous sayings. The most sought-after of all chamberpots for collectors are those with the images of political figures painted or glazed on the target area... one memorable late model featured Hitler, with the motto "Here's one on Old Stinky... another invasion of Poland."