What is the metric term for one thousandth?

The correct answer is milli, which is the metric term for one thousandth (1/1000) of a unit. In the metric system, prefixes are used to indicate different scales or subdivisions of units. The prefix milli is derived from the Latin word "mille," meaning thousand. Therefore, when applied to a meter, for example, one millimeter (mm) equals one one-thousandth of a meter.

Understanding the metric system is essential for accurately measuring and converting quantities, especially in scientific and mathematical contexts. The other prefixes, such as deci (indicating one-tenth, or 1/10) and centi (representing one-hundredth, or 1/100), serve different purposes and relate to different parts of the metric scale, which is why they do not apply to the meaning of one thousandth. The term "base" refers to the standard unit of measure in the metric system, but it does not indicate a specific fraction like milli does.