What term describes the number of waves that pass in one second?

The term that describes the number of waves that pass in one second is frequency. Frequency indicates how often a repeating event occurs over a specific period of time, measured in hertz (Hz), where one hertz equals one wave per second. In the context of waves, this means that if you have a frequency of, for example, 5 Hz, there are five complete waves passing a given point each second.

Wave speed refers to how fast the wave travels through a medium but does not provide information about the number of waves occurring per second. Amplitude measures the height or strength of a wave but does not relate to the speed or number of waves. Wavelength, on the other hand, is the distance between two consecutive points in phase on a wave (such as crest to crest) and does not measure the temporal frequency of wave occurrence. Thus, frequency is the correct term for the concept of wave occurrence per unit time.