ballast

(noun) any heavy material used to stabilize a ship or airship.

(noun) coarse gravel laid to form a bed for streets and railroads.

(noun) an attribute that tends to give stability in character and morals; something that steadies the mind or feelings.

(noun) a resistor inserted into a circuit to compensate for changes (as those arising from temperature fluctuations). Synonyms: ballast resistor, barretter.

(noun) an electrical device for starting and regulating fluorescent and discharge lamps. Synonyms: light ballast.

(verb) make steady with a ballast.