Which term is defined as the number of cycles a signal completes in one second?

The term that is defined as the number of cycles a signal completes in one second is frequency. Frequency is measured in hertz (Hz), where one hertz equates to one cycle per second. This is a fundamental concept in telecommunications and wireless communications because it describes how often a signal oscillates, which directly relates to the signal's ability to carry data.

Understanding frequency is crucial in various applications, such as radio broadcasting, where different frequencies correspond to different channels, and in data transmission, where higher frequencies can allow for more data to be sent simultaneously. Waveform refers to the shape of the signal over time, amplitude represents the height of the signal wave, influencing its power and intensity, and phase deals with the timing of the wave relative to a reference point. Each of these terms is important in the realm of telecommunications, but frequency specifically addresses the rate of cycles per second, making it the correct choice for this question.