Throughout this site we use many technical terms, and given the breadth of readership our site enjoys, sometimes we are remiss and incorrectly assume everyone knows what we are referring to. For those that do not, here are some explanations of the technical terms use.
A resistor which reduces the voltage from the battery to the ignition coil. Cars using this system have a coil which works on about 8 volts, so the resistor is needed to drop the 12 volts from the battery down to this value. During starting, however, when the load from the starter motor reduces the battery voltage, the ballast resistor is bypassed and the coil gets the full available voltage.