Question

The ____ is a measure of the number of waves that pass a point in a given amount of time

Answer 1

It's called the frequency. The waves are measured in Hertz, that are also known as "cycles per second".

Answer 2

The (frequency of the wave multiplied by the number of seconds
in a given amount of time) is the measure of the number of waves that
pass a point in that amount of time.

If you had said "in one second" instead of "in a given amount of time,
then the word in the blank would simply be frequency.