The term "reciprocal frequency" is not a standard term in physics or engineering. It's possible you might be referring to one of these concepts:

1. Period: The period of a wave is the time it takes for one complete cycle to occur. It is the reciprocal of the frequency.

* Formula: Period (T) = 1 / Frequency (f)

2. Wavelength: Wavelength is the distance between two successive crests or troughs of a wave. It is related to frequency and the wave's speed.

* Formula: Wavelength (λ) = Speed (v) / Frequency (f)

3. Angular Frequency: In some contexts, you might encounter "angular frequency," denoted by ω (omega), which is related to the regular frequency (f) by:

* Formula: ω = 2πf

If you can provide more context about where you encountered "reciprocal frequency," I might be able to give you a more specific answer.