The property or condition of occurring at frequent intervals. Mathematics & Physics The number of times a specified periodic phenomenon occurs within a specified interval, as: Mathematics & Physics The number of repetitions of a complete sequence of values of a periodic function per unit variation of an independent variable. Mathematics & Physics The number of complete cycles of a periodic process occurring per unit time. Mathematics & Physics The number of repetitions per unit time of a complete waveform, as of an electric current. Statistics The number of measurements in an interval of a frequency distribution. Statistics The ratio of the number of times an event occurs in a series of trials of a chance experiment to the number of trials of the experiment performed.