Final answer:
Frequency is the term that describes the number of times a receiver is exposed to a message within a specific time frame and is also used in the context of waves to denote the number of occurrences of a repeating event per unit time.
Step-by-step explanation:
The number of times a receiver is exposed to a message in a given time period is known as Frequency. This term is used in various contexts, such as in media and advertising, where it denotes the number of times an audience sees or hears a particular advertisement or message over a specified period. In the context of waves, such as sound waves or electromagnetic waves, frequency refers to the number of occurrences of a repeating event per unit time, which is measured in hertz (Hz).