Final answer:
The term for a rate that compares a quantity to exactly one unit of another quantity is known as a unit rate.
Step-by-step explanation:
The term that is a rate comparing a quantity to exactly one unit of another quantity is known as a unit rate. A unit rate is a special kind of ratio where one of the quantities is expressed as a quantity per one unit of the other quantity. An example of a unit rate is traveling at 55 miles per hour, which can be written as 55 miles/1 hour. Unit rates are commonly used to compare prices, speeds, densities, and other quantities in which comparisons to a single unit are useful.