n. 1.any heavy material used to stabilize a ship or airship 2.coarse gravel laid to form a bed for streets and railroads 3.an attribute that tends to give stability in character and morals 4.a resistor inserted into a circuit to compensate for changes (as those arising from temperature fluctuations) 5.an electrical device for starting and regulating fluorescent and discharge lamps ballast v. 1.make steady with a ballast