the number of observations in a given statistical category
the ratio of the number of observations in a statistical category to the total number of observations
the number of occurrences within a given time period; "the frequency of modulation was 40 cycles per second"; "the frequency of his seizures increased as he grew older"
the ordinary members of an organization (such as the enlisted soldiers of an army); "the strike was supported by the union rank and file"; "he rose from the ranks to become a colonel"