definitions

# frequency

[free-kwuhn-see]
noun, plural fre·quen·cies.
1. Also fre·quence. the state or fact of being frequent; frequent occurrence: We are alarmed by the frequency of fires in the neighborhood.
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. Symbol: F; Abbreviation: 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.

## Origin of frequency

First recorded in 1545–55, frequency is from the Latin word frequentia assembly, multitude, crowd. See frequent, -cy
Related formsnon·fre·quence, nounnon·fre·quen·cy, nouno·ver·fre·quen·cy, nounun·der·fre·quen·cy, noun, plural un·der·fre·quen·cies.

## Synonyms for frequency

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for under-frequency

## frequency

noun plural -cies
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. 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 hertzSymbol: ν, f
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
Also called (for senses 1, 2): frequence

## Word Origin for frequency

C16: from Latin frequentia a large gathering, from frequēns numerous, crowded
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for under-frequency

## frequency

n.

1640s, "fact of occurring often," from Latin frequentia "a crowding, crowd," from frequentem (see frequent).

Earlier it had been used in a now-obsolete sense of "state of being crowded" (mid-16c.); sense in physics, "rate of recurrence," especially of a vibration, is from 1831. In radio electronics, frequency modulation (1922, abbreviated F.M.) as a system of broadcasting is distinguished from amplitude modulation (or A.M.).

Online Etymology Dictionary, © 2010 Douglas Harper

under-frequency in Science

## frequency

[frēkwən-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. Compare amplitude. See also period.
2. Mathematics The ratio of the number of occurrences of some event to the number of opportunities for its occurrence.