Other forms: frequencies
Frequency is how many times per second a wave repeats. A frequency of fifty hertz, high frequency, the radio frequency.
It is measured in hertz, one hertz being one cycle per second, and it decides the pitch of a sound and the colour of light. Radio stations are identified by frequency, and the whole spectrum is regulated and sold. The everyday sense is simply how often something happens: the frequency of the buses, increase the frequency. Note frequent, both adjective and verb, with the stress in different places.
Latin frequentia means a crowding together, from frequens, crowded. The word meant a large gathering before it meant repetition, and the modern sense is about events crowding into a period rather than people into a room.
Latin
frequentia
English, today
frequency
From Latin frequentia, from frequens. by surface analysis, frequent + -cy.
Etymology from Wiktionary, CC BY-SA