**:**the fact or condition of occurring frequently

- the frequency of automobile accidents

**:**the number of times that a periodic function repeats the same sequence of values during a unit variation of the independent variable

**:**the number, proportion, or percentage of items in a particular category in a set of data

**:**the number of repetitions of a periodic process in a unit of time: such as

**:**the number of complete alternations (see alternation 1) per second of an alternating current

**:**the number of complete oscillations (see oscillation 3) per second of energy (such as sound or electromagnetic radiation) in the form of waves