Definitions of ballast:

• noun:   any heavy material used to stabilize a ship or airship
• noun:   an electrical device for starting and regulating fluorescent and discharge lamps
• noun:   an attribute that tends to give stability in character and morals; something that steadies the mind or feelings
• noun:   coarse gravel laid to form a bed for streets and railroads
• noun:   a resistor inserted into a circuit to compensate for changes (as those arising from temperature fluctuations)
• verb:   make steady with a ballast