What is the term for one thousandth of an ampere?

The correct term for one thousandth of an ampere is "milliampere."

This unit of measurement is commonly used in electrical applications and signifies that one milliampere (mA) is equal to 0.001 amperes (A). The prefix "milli-" indicates a factor of one thousandth. This unit is particularly useful when dealing with low currents, such as those encountered in various electronics and medical devices, because it allows for more manageable figures rather than using the larger ampere unit.

In contrast, the other terms presented do not relate to this specific measure of current. An ampere is the base unit of electric current in the International System of Units (SI). A kilovolt measures electric potential and represents one thousand volts. A decibel, on the other hand, is a unit used to measure sound intensity and is not relevant to electrical current measurements.