Frequency
Part of speech: noun
Definition: The rate of occurrence of anything; the relationship between incidence and time period. The property of occurring often rather than infrequently. The quotient of the number of times n a periodic phenomenon occurs over the time t in which it occurs: f = n / t.
Hertz
Part of speech: noun
Definition: In the International System of Units, the derived unit of frequency; one (period or cycle of any periodic event) per second. Symbol: Hz