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frequency

FREE-kwun-see /ˈfriː.kwən.si/

nounB1GRESATACTTOEFL

academicscientificgeneral

The rate at which a vibration or wave occurs that constitutes a wave, usually measured per second; the state of being frequent.

In acoustics, higher frequency corresponds directly to a higher perceived pitch in sound.

The story behind the word. Derived from Latin 'frequentia', meaning a crowd or repeated occurrence, from 'frequens' (crammed). 19th-century physicists adopted the term to describe how closely packed together wave crests are in time.

Word relationships

pitch rate: 'Pitch rate' describes musical perception, whereas 'frequency' is the exact physical measurement in hertz.
repetition rate: 'Repetition rate' applies to general events, whereas 'frequency' specifically measures wave cycles per second in physics.

infrequency: Refers to rare or non-repeating events.

Commonly confused with

wavelength: Frequency and wavelength are inversely proportional: as frequency increases, wavelength decreases.

Word family

frequent (adjective): Occurring often or at short intervals.
frequently (adverb): Many times at short intervals.

Collocations

high frequency
low frequency
frequency range
resonant frequency

Example sentences

"Human ears can generally detect sound waves across a frequency range from twenty hertz to twenty kilohertz." Acoustic Physics
"The broadcast tower shifted its transmission frequency to eliminate interference with neighboring radio channels." Radio Engineering

Memory hook

FREQUENT events happen often; FREQUENCY measures how often wave crests hit per second. FREQUENCY counts wave cycles per second.

When not to use

Do not confuse frequency (how often waves repeat) with amplitude (how tall waves are).

Fun facts

Dog whistles work because dogs can hear sound frequencies up to 45,000 Hz, whereas human hearing cuts off around 20,000 Hz.