frequency

American  

[free-kwuhn-see] / ˈfri kwən si /

noun

plural

frequencies

1. Also frequence. the state or fact of being frequent; frequent occurrence.

   We are alarmed by the frequency of fires in the neighborhood.

   Synonyms:

   recurrence, repetition, regularity

2. rate of occurrence.

   The doctor has increased the frequency of his visits.

3. Physics.

   1. the number of periods or regularly occurring events of any given kind in unit of time, usually in one second.

   2. the number of cycles or completed alternations per unit time of a wave or oscillation. F; freq.

4. Mathematics. the number of times a value recurs in a unit change of the independent variable of a given function.

5. Statistics. the number of items occurring in a given category.

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frequency British  

/ ˈfriːkwənsɪ /

noun

1. the state of being frequent; frequent occurrence

2. the number of times that an event occurs within a given period; rate of recurrence

3.  ν.   f.  physics the number of times that a periodic function or vibration repeats itself in a specified time, often 1 second. It is usually measured in hertz

4. statistics

   1. the number of individuals in a class ( absolute frequency )

   2. the ratio of this number to the total number of individuals under survey ( relative frequency )

5. ecology

   1. the number of individuals of a species within a given area

   2. the percentage of quadrats that contains individuals of a species

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frequency Scientific  

/ frē′kwən-sē /

1. Physics The rate at which a repeating event occurs, such as the full cycle of a wave. Frequencies are usually measured in hertz.

2. Physics Compare amplitude See also period

3. Mathematics The ratio of the number of occurrences of some event to the number of opportunities for its occurrence.

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frequency Cultural  

1. In physics, the number of crests of a wave that move past a given point in a given unit of time. The most common unit of frequency is the hertz (Hz), corresponding to one crest per second. The frequency of a wave can be calculated by dividing the speed of the wave by the wavelength. Thus, in the electromagnetic spectrum, the wavelengths decrease as the frequencies increase, and vice versa.

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Other Word Forms

• nonfrequence noun
• nonfrequency noun
• overfrequency noun
• underfrequency noun

Etymology

Origin of frequency

First recorded in 1545–55, frequency is from the Latin word frequentia assembly, multitude, crowd. See frequent, -cy

Explanation

Frequency measures how often things repeat over time. City buses often reach stops at a frequency of every 15 minutes, unless it's snowing or raining really hard. In that case, the frequency will slow. You probably know the word frequent, a synonym for often. So, it is tempting to think frequency describes something that happens often. However, this isn't true: frequency describes any rate of time at which something repeats. For example, from Earth, Halley's Comet is visible at a frequency of 76 years — it's not frequent, but it is on schedule.

Example Sentences

United Parcel Service has invested $100 million to date in radio frequency identification technology to track packages across its U.S. network.

From The Wall Street Journal • Apr. 14, 2026

In the Southland, strong El Niños increase the likelihood of wet winters that replenish water supplies and decrease wildfire frequency but can also lead to flooding, debris flows and coastal erosion.

From Los Angeles Times • Apr. 10, 2026

They quickly return to a lower energy state by releasing light at a specific frequency, a process known as spontaneous emission.

From Science Daily • Apr. 10, 2026

The frequency and cost of climate-influenced disasters, including severe storms, drought and flooding, continues to mount — between $350 billion and $450 billion in each of the last three years — stretching government budgets.

From Salon • Apr. 10, 2026

The number beneath a note tells you the relationship of that note's frequency to the frequency of the first note in the series — the fundamental.

From "Understanding Basic Music Theory" by Catherine Schmidt-Jones and Russel Jones

Related Words

• density
• number
• prevalence
• recurrence
• regularity
• repetition