Frequence

[free-kwuh n-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.
2.
rate of occurrence:
The doctor has increased the frequency of his visits.
3.
Physics.

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.
/ˈfriːkwənsɪ/
noun (pl) -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 hertz ν, f
4.
(statistics)

5.
(ecology)

n.

1530s, from French fréquence, from Latin frequentia (see frequent).
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.).
frequency
(frē’kwən-sē)

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.