the ratio of the number of observations in a statistical category to the total number of observations
"The bar chart shows that the frequency of customers returning on weekends was twice as high as during weekdays."
the number of observations in a given statistical category
"The survey results showed that the frequency of respondents choosing option B was significantly higher than any other choice."
The rate of occurrence of anything; the relationship between incidence and time period.
"The frequency of thunderstorms in this region peaks during the summer months, occurring almost daily at that time."
In plain English: Frequency is how often something happens or occurs within a specific amount of time.
"The frequency of his visits to the gym increased after he decided to get fit."
Usage: Use frequency to describe how often something happens within a specific amount of time, such as checking your email multiple times a day. Avoid confusing it with quantity, which refers to the total number of items rather than the rate of their occurrence.
The word frequency comes from the Latin frequentia, which was derived from frequens. It entered English through a straightforward combination of the root meaning "often" and the suffix "-cy.