An appliance that allows an object (such as a ship's compass) to remain horizontal even as its support tips source: WordNet 3.0A contrivance for permitting a body to incline freely in all directions, or for suspending anything, as abarometer, ship's compass, chronometer, etc., so that it will remain plumb, or level, when its support is tipped, as by the rolling of a ship. It consists of a ring in which the body can turn on an axis through a diameter of the ring, while the ring itself is so pivoted to its support that it can turn about a diameter at right angles to the first.