The prefix "milli-" is used to denote which of the following units?

The prefix "milli-" is a metric system prefix that indicates a factor of one-thousandth, or 1/1000. This means that when "milli-" is attached to a unit of measure, it represents a measurement that is 1/1000 of that unit. For example, one millimeter (mm) is equal to one-thousandth of a meter. This prefix is widely used in scientific and technical contexts, particularly in fields such as medicine, engineering, and physics, to denote small quantities in a standardized way.

The other options reflect different prefixes: "centi-" signifies 1/100, "deci-" represents 1/10, and the prefix "deca-" or "hecto-" relates to 1/10000 in other contexts, but do not align with the meaning of "milli-." Therefore, "milli-" is uniquely defined as 1/1000, making it the only correct choice related to this query.