Final answer:
The correct term that defines a measurement which changes value depending on the medication's potency is 'International unit (IU)'. This measurement accounts for biological activity and potency, unlike volume or other chemical property-based measurements like cubic centimeter, millimoles, or milliequivalents.
Step-by-step explanation:
The term that defines 'a measurement of the amount of an ingredient in a medication, but its value changes depending on the potency of the medication' is International unit (IU). This unit is used when the potency of the active substance is an important factor in its effect, and it varies from one substance to another, thus requiring standardization based on its biological activity. The International unit is not a fixed quantity but is established for each substance through biological assays and is used for vitamins, hormones, some medications, vaccines, and other biological agents. It's important to note that other units of measurements like cubic centimeter (CC), millimoles (mmol), and milliequivalents (mEq) are used to measure different aspects of substances. A cubic centimeter is a unit of volume equivalent to a milliliter and doesn't change with substance potency, while millimoles and milliequivalents are units that related to the amount of a substance based on its chemical properties rather than biological activity.